diff --git a/apps/openmw/mwclass/actor.cpp b/apps/openmw/mwclass/actor.cpp
index 77bfaddf64..4157a03bc0 100644
--- a/apps/openmw/mwclass/actor.cpp
+++ b/apps/openmw/mwclass/actor.cpp
@@ -73,9 +73,9 @@ namespace MWClass
     {
         float weight = getContainerStore(ptr).getWeight();
         const MWMechanics::MagicEffects& effects = getCreatureStats(ptr).getMagicEffects();
-        weight -= effects.get(MWMechanics::EffectKey(ESM::MagicEffect::Feather)).getMagnitude();
+        weight -= effects.getOrDefault(MWMechanics::EffectKey(ESM::MagicEffect::Feather)).getMagnitude();
         if (ptr != MWMechanics::getPlayer() || !MWBase::Environment::get().getWorld()->getGodModeState())
-            weight += effects.get(MWMechanics::EffectKey(ESM::MagicEffect::Burden)).getMagnitude();
+            weight += effects.getOrDefault(MWMechanics::EffectKey(ESM::MagicEffect::Burden)).getMagnitude();
         return (weight < 0) ? 0.0f : weight;
     }
 
diff --git a/apps/openmw/mwclass/actor.hpp b/apps/openmw/mwclass/actor.hpp
index fae31b8d20..5a143c7a7d 100644
--- a/apps/openmw/mwclass/actor.hpp
+++ b/apps/openmw/mwclass/actor.hpp
@@ -28,7 +28,7 @@ namespace MWClass
         float getSwimSpeedImpl(const MWWorld::Ptr& ptr, const GMST& gmst, const MWMechanics::MagicEffects& mageffects,
             float baseSpeed) const
         {
-            return baseSpeed * (1.0f + 0.01f * mageffects.get(ESM::MagicEffect::SwiftSwim).getMagnitude())
+            return baseSpeed * (1.0f + 0.01f * mageffects.getOrDefault(ESM::MagicEffect::SwiftSwim).getMagnitude())
                 * (gmst.fSwimRunBase->mValue.getFloat()
                     + 0.01f * getSkill(ptr, ESM::Skill::Athletics) * gmst.fSwimRunAthleticsMult->mValue.getFloat());
         }
diff --git a/apps/openmw/mwclass/creature.cpp b/apps/openmw/mwclass/creature.cpp
index 7ea0c7c111..39de4a5b1d 100644
--- a/apps/openmw/mwclass/creature.cpp
+++ b/apps/openmw/mwclass/creature.cpp
@@ -555,11 +555,11 @@ namespace MWClass
         if (getEncumbrance(ptr) > getCapacity(ptr))
             moveSpeed = 0.0f;
         else if (canFly(ptr)
-            || (mageffects.get(ESM::MagicEffect::Levitate).getMagnitude() > 0 && world->isLevitationEnabled()))
+            || (mageffects.getOrDefault(ESM::MagicEffect::Levitate).getMagnitude() > 0 && world->isLevitationEnabled()))
         {
             float flySpeed = 0.01f
                 * (stats.getAttribute(ESM::Attribute::Speed).getModified()
-                    + mageffects.get(ESM::MagicEffect::Levitate).getMagnitude());
+                    + mageffects.getOrDefault(ESM::MagicEffect::Levitate).getMagnitude());
             flySpeed = gmst.fMinFlySpeed->mValue.getFloat()
                 + flySpeed * (gmst.fMaxFlySpeed->mValue.getFloat() - gmst.fMinFlySpeed->mValue.getFloat());
             const float normalizedEncumbrance = getNormalizedEncumbrance(ptr);
@@ -614,7 +614,7 @@ namespace MWClass
     float Creature::getArmorRating(const MWWorld::Ptr& ptr) const
     {
         // Equipment armor rating is deliberately ignored.
-        return getCreatureStats(ptr).getMagicEffects().get(ESM::MagicEffect::Shield).getMagnitude();
+        return getCreatureStats(ptr).getMagicEffects().getOrDefault(ESM::MagicEffect::Shield).getMagnitude();
     }
 
     float Creature::getCapacity(const MWWorld::Ptr& ptr) const
diff --git a/apps/openmw/mwclass/npc.cpp b/apps/openmw/mwclass/npc.cpp
index d734a3868c..7aba7b2b50 100644
--- a/apps/openmw/mwclass/npc.cpp
+++ b/apps/openmw/mwclass/npc.cpp
@@ -1021,11 +1021,11 @@ namespace MWClass
         float moveSpeed;
         if (getEncumbrance(ptr) > getCapacity(ptr))
             moveSpeed = 0.0f;
-        else if (mageffects.get(ESM::MagicEffect::Levitate).getMagnitude() > 0 && world->isLevitationEnabled())
+        else if (mageffects.getOrDefault(ESM::MagicEffect::Levitate).getMagnitude() > 0 && world->isLevitationEnabled())
         {
             float flySpeed = 0.01f
                 * (stats.getAttribute(ESM::Attribute::Speed).getModified()
-                    + mageffects.get(ESM::MagicEffect::Levitate).getMagnitude());
+                    + mageffects.getOrDefault(ESM::MagicEffect::Levitate).getMagnitude());
             flySpeed = gmst.fMinFlySpeed->mValue.getFloat()
                 + flySpeed * (gmst.fMaxFlySpeed->mValue.getFloat() - gmst.fMinFlySpeed->mValue.getFloat());
             flySpeed *= 1.0f - gmst.fEncumberedMoveEffect->mValue.getFloat() * normalizedEncumbrance;
@@ -1071,7 +1071,7 @@ namespace MWClass
         float x = gmst.fJumpAcrobaticsBase->mValue.getFloat()
             + std::pow(a / 15.0f, gmst.fJumpAcroMultiplier->mValue.getFloat());
         x += 3.0f * b * gmst.fJumpAcroMultiplier->mValue.getFloat();
-        x += mageffects.get(ESM::MagicEffect::Jump).getMagnitude() * 64;
+        x += mageffects.getOrDefault(ESM::MagicEffect::Jump).getMagnitude() * 64;
         x *= encumbranceTerm;
 
         if (stats.getStance(MWMechanics::CreatureStats::Stance_Run))
@@ -1217,7 +1217,7 @@ namespace MWClass
             }
         }
 
-        float shield = stats.getMagicEffects().get(ESM::MagicEffect::Shield).getMagnitude();
+        float shield = stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Shield).getMagnitude();
 
         return ratings[MWWorld::InventoryStore::Slot_Cuirass] * 0.3f
             + (ratings[MWWorld::InventoryStore::Slot_CarriedLeft] + ratings[MWWorld::InventoryStore::Slot_Helmet]
diff --git a/apps/openmw/mwdialogue/filter.cpp b/apps/openmw/mwdialogue/filter.cpp
index 0ad82be488..c5ec812a8f 100644
--- a/apps/openmw/mwdialogue/filter.cpp
+++ b/apps/openmw/mwdialogue/filter.cpp
@@ -582,7 +582,7 @@ bool MWDialogue::Filter::getSelectStructBoolean(const SelectWrapper& select) con
             return player.getClass()
                        .getCreatureStats(player)
                        .getMagicEffects()
-                       .get(ESM::MagicEffect::Corprus)
+                       .getOrDefault(ESM::MagicEffect::Corprus)
                        .getMagnitude()
                 != 0;
 
@@ -601,7 +601,7 @@ bool MWDialogue::Filter::getSelectStructBoolean(const SelectWrapper& select) con
             return player.getClass()
                        .getCreatureStats(player)
                        .getMagicEffects()
-                       .get(ESM::MagicEffect::Vampirism)
+                       .getOrDefault(ESM::MagicEffect::Vampirism)
                        .getMagnitude()
                 > 0;
 
diff --git a/apps/openmw/mwgui/spellcreationdialog.cpp b/apps/openmw/mwgui/spellcreationdialog.cpp
index 7039c757e3..a1d3ea6f9f 100644
--- a/apps/openmw/mwgui/spellcreationdialog.cpp
+++ b/apps/openmw/mwgui/spellcreationdialog.cpp
@@ -37,8 +37,8 @@ namespace
         const MWWorld::Store<ESM::GameSetting>& gmst
             = MWBase::Environment::get().getESMStore()->get<ESM::GameSetting>();
 
-        return gmst.find(ESM::MagicEffect::effectIdToGmstString(id1))->mValue.getString()
-            < gmst.find(ESM::MagicEffect::effectIdToGmstString(id2))->mValue.getString();
+        return gmst.find(ESM::MagicEffect::indexToGmstString(id1))->mValue.getString()
+            < gmst.find(ESM::MagicEffect::indexToGmstString(id2))->mValue.getString();
     }
 
     void init(ESM::ENAMstruct& effect)
@@ -196,7 +196,7 @@ namespace MWGui
         mEffectImage->setImageTexture(Misc::ResourceHelpers::correctIconPath(
             effect->mIcon, MWBase::Environment::get().getResourceSystem()->getVFS()));
 
-        mEffectName->setCaptionWithReplacing("#{" + ESM::MagicEffect::effectIdToGmstString(effect->mIndex) + "}");
+        mEffectName->setCaptionWithReplacing("#{" + ESM::MagicEffect::indexToGmstString(effect->mIndex) + "}");
 
         mEffect.mEffectID = effect->mIndex;
 
@@ -552,7 +552,7 @@ namespace MWGui
             mAvailableEffectsList->addItem(MWBase::Environment::get()
                                                .getESMStore()
                                                ->get<ESM::GameSetting>()
-                                               .find(ESM::MagicEffect::effectIdToGmstString(effectId))
+                                               .find(ESM::MagicEffect::indexToGmstString(effectId))
                                                ->mValue.getString());
             mButtonMapping[i] = effectId;
             ++i;
@@ -565,7 +565,7 @@ namespace MWGui
             const std::string& name = MWBase::Environment::get()
                                           .getESMStore()
                                           ->get<ESM::GameSetting>()
-                                          .find(ESM::MagicEffect::effectIdToGmstString(effectId))
+                                          .find(ESM::MagicEffect::indexToGmstString(effectId))
                                           ->mValue.getString();
             MyGUI::Widget* w = mAvailableEffectsList->getItemWidget(name);
 
diff --git a/apps/openmw/mwgui/spellicons.cpp b/apps/openmw/mwgui/spellicons.cpp
index d8747d2426..ba94eaba95 100644
--- a/apps/openmw/mwgui/spellicons.cpp
+++ b/apps/openmw/mwgui/spellicons.cpp
@@ -162,7 +162,7 @@ namespace MWGui
                     image->setImageTexture(Misc::ResourceHelpers::correctIconPath(
                         effect->mIcon, MWBase::Environment::get().getResourceSystem()->getVFS()));
 
-                    const std::string& name = ESM::MagicEffect::effectIdToGmstString(effectId);
+                    const std::string& name = ESM::MagicEffect::indexToGmstString(effectId);
 
                     ToolTipInfo tooltipInfo;
                     tooltipInfo.caption = "#{" + name + "}";
diff --git a/apps/openmw/mwgui/tooltips.cpp b/apps/openmw/mwgui/tooltips.cpp
index 5b152fe5b8..2904f20236 100644
--- a/apps/openmw/mwgui/tooltips.cpp
+++ b/apps/openmw/mwgui/tooltips.cpp
@@ -954,7 +954,7 @@ namespace MWGui
     void ToolTips::createMagicEffectToolTip(MyGUI::Widget* widget, short id)
     {
         const ESM::MagicEffect* effect = MWBase::Environment::get().getESMStore()->get<ESM::MagicEffect>().find(id);
-        const std::string& name = ESM::MagicEffect::effectIdToGmstString(id);
+        const std::string& name = ESM::MagicEffect::indexToGmstString(id);
 
         std::string icon = effect->mIcon;
         int slashPos = icon.rfind('\\');
diff --git a/apps/openmw/mwlua/magicbindings.cpp b/apps/openmw/mwlua/magicbindings.cpp
index 2b4afab6d1..e5723f1c34 100644
--- a/apps/openmw/mwlua/magicbindings.cpp
+++ b/apps/openmw/mwlua/magicbindings.cpp
@@ -191,7 +191,7 @@ namespace MWLua
 
         sol::table effect(context.mLua->sol(), sol::create);
         magicApi["EFFECT_TYPE"] = LuaUtil::makeStrictReadOnly(effect);
-        for (const auto& name : ESM::MagicEffect::sEffectNames)
+        for (const auto& name : ESM::MagicEffect::sIndexNames)
         {
             effect[name] = Misc::StringUtils::lowerCase(name);
         }
@@ -263,7 +263,7 @@ namespace MWLua
         auto effectParamsT = lua.new_usertype<ESM::ENAMstruct>("ESM3_EffectParams");
         effectParamsT[sol::meta_function::to_string] = [magicEffectStore](const ESM::ENAMstruct& params) {
             const ESM::MagicEffect* const rec = magicEffectStore->find(params.mEffectID);
-            return "ESM3_EffectParams[" + ESM::MagicEffect::effectIdToGmstString(rec->mIndex) + "]";
+            return "ESM3_EffectParams[" + ESM::MagicEffect::indexToGmstString(rec->mIndex) + "]";
         };
         effectParamsT["effect"]
             = sol::readonly_property([magicEffectStore](const ESM::ENAMstruct& params) -> const ESM::MagicEffect* {
@@ -296,10 +296,10 @@ namespace MWLua
         auto magicEffectT = context.mLua->sol().new_usertype<ESM::MagicEffect>("ESM3_MagicEffect");
 
         magicEffectT[sol::meta_function::to_string] = [](const ESM::MagicEffect& rec) {
-            return "ESM3_MagicEffect[" + ESM::MagicEffect::effectIdToGmstString(rec.mIndex) + "]";
+            return "ESM3_MagicEffect[" + ESM::MagicEffect::indexToGmstString(rec.mIndex) + "]";
         };
         magicEffectT["id"] = sol::readonly_property([](const ESM::MagicEffect& rec) -> std::string {
-            auto name = ESM::MagicEffect::effectIdToName(rec.mIndex);
+            auto name = ESM::MagicEffect::indexToName(rec.mIndex);
             return Misc::StringUtils::lowerCase(name);
         });
         magicEffectT["name"] = sol::readonly_property([](const ESM::MagicEffect& rec) -> std::string_view {
@@ -307,7 +307,7 @@ namespace MWLua
                 .getWorld()
                 ->getStore()
                 .get<ESM::GameSetting>()
-                .find(ESM::MagicEffect::effectIdToGmstString(rec.mIndex))
+                .find(ESM::MagicEffect::indexToGmstString(rec.mIndex))
                 ->mValue.getString();
         });
         magicEffectT["school"]
@@ -327,10 +327,10 @@ namespace MWLua
         auto activeEffectT = context.mLua->sol().new_usertype<ActiveEffect>("ActiveEffect");
 
         activeEffectT[sol::meta_function::to_string] = [](const ActiveEffect& effect) {
-            return "ActiveEffect[" + ESM::MagicEffect::effectIdToGmstString(effect.key.mId) + "]";
+            return "ActiveEffect[" + ESM::MagicEffect::indexToGmstString(effect.key.mId) + "]";
         };
         activeEffectT["id"] = sol::readonly_property([](const ActiveEffect& effect) -> std::string {
-            auto name = ESM::MagicEffect::effectIdToName(effect.key.mId);
+            auto name = ESM::MagicEffect::indexToName(effect.key.mId);
             return Misc::StringUtils::lowerCase(name);
         });
         activeEffectT["name"]
@@ -570,7 +570,7 @@ namespace MWLua
             if (!effects.isActor())
                 return sol::nullopt;
 
-            auto id = ESM::MagicEffect::effectNameToId(idStr);
+            auto id = ESM::MagicEffect::indexNameToIndex(idStr);
             auto* rec = MWBase::Environment::get().getWorld()->getStore().get<ESM::MagicEffect>().find(id);
 
             MWMechanics::EffectKey key = MWMechanics::EffectKey(id);
@@ -586,10 +586,10 @@ namespace MWLua
                     key = MWMechanics::EffectKey(id, ESM::Skill::stringToSkillId(argStr.value()));
             }
 
-            MWMechanics::EffectParam param;
+            std::optional<MWMechanics::EffectParam> param;
             if (auto* store = effects.getStore())
                 if (store->get(key, param))
-                    return ActiveEffect{ key, param };
+                    return ActiveEffect{ key, param.value() };
             return sol::nullopt;
         };
     }
diff --git a/apps/openmw/mwmechanics/activespells.cpp b/apps/openmw/mwmechanics/activespells.cpp
index 69c73c2130..65683ea2b5 100644
--- a/apps/openmw/mwmechanics/activespells.cpp
+++ b/apps/openmw/mwmechanics/activespells.cpp
@@ -374,7 +374,7 @@ namespace MWMechanics
         {
             ESM::MagicEffect::Effects effect
                 = ptr.getClass().isNpc() ? ESM::MagicEffect::CalmHumanoid : ESM::MagicEffect::CalmCreature;
-            if (creatureStats.getMagicEffects().get(effect).getMagnitude() > 0.f)
+            if (creatureStats.getMagicEffects().getOrDefault(effect).getMagnitude() > 0.f)
                 creatureStats.getAiSequence().stopCombat();
         }
     }
diff --git a/apps/openmw/mwmechanics/actors.cpp b/apps/openmw/mwmechanics/actors.cpp
index dddf3f5ec9..20e765fc5e 100644
--- a/apps/openmw/mwmechanics/actors.cpp
+++ b/apps/openmw/mwmechanics/actors.cpp
@@ -158,7 +158,7 @@ namespace
     void soulTrap(const MWWorld::Ptr& creature)
     {
         const auto& stats = creature.getClass().getCreatureStats(creature);
-        if (!stats.getMagicEffects().get(ESM::MagicEffect::Soultrap).getMagnitude())
+        if (!stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Soultrap).getMagnitude())
             return;
         const int creatureSoulValue = creature.get<ESM::Creature>()->mBase->mData.mSoul;
         if (creatureSoulValue == 0)
@@ -668,7 +668,7 @@ namespace MWMechanics
             }
         }
 
-        if (creatureStats2.getMagicEffects().get(ESM::MagicEffect::Invisibility).getMagnitude() > 0)
+        if (creatureStats2.getMagicEffects().getOrDefault(ESM::MagicEffect::Invisibility).getMagnitude() > 0)
             return;
 
         // Stop here if target is unreachable
@@ -828,7 +828,8 @@ namespace MWMechanics
             stats.setHealth(stat);
 
             double restoreHours = hours;
-            const bool stunted = stats.getMagicEffects().get(ESM::MagicEffect::StuntedMagicka).getMagnitude() > 0;
+            const bool stunted
+                = stats.getMagicEffects().getOrDefault(ESM::MagicEffect::StuntedMagicka).getMagnitude() > 0;
             if (stunted)
             {
                 // Stunted Magicka effect should be taken into account.
@@ -954,7 +955,7 @@ namespace MWMechanics
         const bool knockedOutUnderwater
             = (isKnockedOut && world->isUnderwater(ptr.getCell(), osg::Vec3f(ptr.getRefData().getPosition().asVec3())));
         if ((world->isSubmerged(ptr) || knockedOutUnderwater)
-            && stats.getMagicEffects().get(ESM::MagicEffect::WaterBreathing).getMagnitude() == 0)
+            && stats.getMagicEffects().getOrDefault(ESM::MagicEffect::WaterBreathing).getMagnitude() == 0)
         {
             float timeLeft = 0.0f;
             if (knockedOutUnderwater)
@@ -1110,7 +1111,7 @@ namespace MWMechanics
 
         if (actorClass.isClass(ptr, "Guard") && !creatureStats.getAiSequence().isInPursuit()
             && !creatureStats.getAiSequence().isInCombat()
-            && creatureStats.getMagicEffects().get(ESM::MagicEffect::CalmHumanoid).getMagnitude() == 0)
+            && creatureStats.getMagicEffects().getOrDefault(ESM::MagicEffect::CalmHumanoid).getMagnitude() == 0)
         {
             const MWWorld::ESMStore& esmStore = world->getStore();
             static const int cutoff = esmStore.get<ESM::GameSetting>().find("iCrimeThreshold")->mValue.getInteger();
@@ -1814,7 +1815,8 @@ namespace MWMechanics
 
                 // Reset magic effects and recalculate derived effects
                 // One case where we need this is to make sure bound items are removed upon death
-                const float vampirism = stats.getMagicEffects().get(ESM::MagicEffect::Vampirism).getMagnitude();
+                const float vampirism
+                    = stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Vampirism).getMagnitude();
                 stats.getActiveSpells().clear(actor.getPtr());
                 // Make sure spell effects are removed
                 purgeSpellEffects(stats.getActorId());
@@ -2002,7 +2004,7 @@ namespace MWMechanics
         const auto [healthPerHour, magickaPerHour] = getRestorationPerHourOfSleep(ptr);
 
         CreatureStats& stats = ptr.getClass().getCreatureStats(ptr);
-        const bool stunted = stats.getMagicEffects().get(ESM::MagicEffect::StuntedMagicka).getMagnitude() > 0;
+        const bool stunted = stats.getMagicEffects().getOrDefault(ESM::MagicEffect::StuntedMagicka).getMagnitude() > 0;
 
         const float healthHours = healthPerHour > 0
             ? (stats.getHealth().getModified() - stats.getHealth().getCurrent()) / healthPerHour
diff --git a/apps/openmw/mwmechanics/actorutil.cpp b/apps/openmw/mwmechanics/actorutil.cpp
index 5b255b3d78..c414ff3032 100644
--- a/apps/openmw/mwmechanics/actorutil.cpp
+++ b/apps/openmw/mwmechanics/actorutil.cpp
@@ -32,13 +32,13 @@ namespace MWMechanics
     bool hasWaterWalking(const MWWorld::Ptr& actor)
     {
         const MWMechanics::MagicEffects& effects = actor.getClass().getCreatureStats(actor).getMagicEffects();
-        return effects.get(ESM::MagicEffect::WaterWalking).getMagnitude() > 0;
+        return effects.getOrDefault(ESM::MagicEffect::WaterWalking).getMagnitude() > 0;
     }
 
     bool isTargetMagicallyHidden(const MWWorld::Ptr& actor)
     {
         const MagicEffects& magicEffects = actor.getClass().getCreatureStats(actor).getMagicEffects();
-        return (magicEffects.get(ESM::MagicEffect::Invisibility).getMagnitude() > 0)
-            || (magicEffects.get(ESM::MagicEffect::Chameleon).getMagnitude() > 75);
+        return (magicEffects.getOrDefault(ESM::MagicEffect::Invisibility).getMagnitude() > 0)
+            || (magicEffects.getOrDefault(ESM::MagicEffect::Chameleon).getMagnitude() > 75);
     }
 }
diff --git a/apps/openmw/mwmechanics/aicombataction.cpp b/apps/openmw/mwmechanics/aicombataction.cpp
index 7981ed123a..86943b1786 100644
--- a/apps/openmw/mwmechanics/aicombataction.cpp
+++ b/apps/openmw/mwmechanics/aicombataction.cpp
@@ -464,7 +464,7 @@ namespace MWMechanics
             if (enemy.getClass()
                     .getCreatureStats(enemy)
                     .getMagicEffects()
-                    .get(ESM::MagicEffect::Levitate)
+                    .getOrDefault(ESM::MagicEffect::Levitate)
                     .getMagnitude()
                 > 0)
             {
@@ -484,7 +484,11 @@ namespace MWMechanics
         if (!actor.getClass().canWalk(actor) && !actor.getClass().isBipedal(actor))
             return true;
 
-        if (actor.getClass().getCreatureStats(actor).getMagicEffects().get(ESM::MagicEffect::Levitate).getMagnitude()
+        if (actor.getClass()
+                .getCreatureStats(actor)
+                .getMagicEffects()
+                .getOrDefault(ESM::MagicEffect::Levitate)
+                .getMagnitude()
             > 0)
             return true;
 
diff --git a/apps/openmw/mwmechanics/character.cpp b/apps/openmw/mwmechanics/character.cpp
index f4f53a7110..38788c3445 100644
--- a/apps/openmw/mwmechanics/character.cpp
+++ b/apps/openmw/mwmechanics/character.cpp
@@ -284,8 +284,11 @@ namespace
         if (fallHeight >= fallDistanceMin)
         {
             const float acrobaticsSkill = static_cast<float>(ptr.getClass().getSkill(ptr, ESM::Skill::Acrobatics));
-            const float jumpSpellBonus
-                = ptr.getClass().getCreatureStats(ptr).getMagicEffects().get(ESM::MagicEffect::Jump).getMagnitude();
+            const float jumpSpellBonus = ptr.getClass()
+                                             .getCreatureStats(ptr)
+                                             .getMagicEffects()
+                                             .getOrDefault(ESM::MagicEffect::Jump)
+                                             .getMagnitude();
             const float fallAcroBase = store.find("fFallAcroBase")->mValue.getFloat();
             const float fallAcroMult = store.find("fFallAcroMult")->mValue.getFloat();
             const float fallDistanceBase = store.find("fFallDistanceBase")->mValue.getFloat();
@@ -2387,7 +2390,11 @@ namespace MWMechanics
         {
             if (cls.getCreatureStats(mPtr).isDead()
                 || (!godmode
-                    && cls.getCreatureStats(mPtr).getMagicEffects().get(ESM::MagicEffect::Paralyze).getModifier() > 0))
+                    && cls.getCreatureStats(mPtr)
+                            .getMagicEffects()
+                            .getOrDefault(ESM::MagicEffect::Paralyze)
+                            .getModifier()
+                        > 0))
             {
                 moved.z() = 1.0;
             }
@@ -2644,7 +2651,7 @@ namespace MWMechanics
                 || mPtr.getClass()
                         .getCreatureStats(mPtr)
                         .getMagicEffects()
-                        .get(MWMechanics::EffectKey(effectId))
+                        .getOrDefault(MWMechanics::EffectKey(effectId))
                         .getMagnitude()
                     <= 0)
                 mAnimation->removeEffect(effectId);
@@ -2656,16 +2663,22 @@ namespace MWMechanics
         if (!mPtr.getClass().isActor())
             return;
 
-        float light
-            = mPtr.getClass().getCreatureStats(mPtr).getMagicEffects().get(ESM::MagicEffect::Light).getMagnitude();
+        float light = mPtr.getClass()
+                          .getCreatureStats(mPtr)
+                          .getMagicEffects()
+                          .getOrDefault(ESM::MagicEffect::Light)
+                          .getMagnitude();
         mAnimation->setLightEffect(light);
 
         // If you're dead you don't care about whether you've started/stopped being a vampire or not
         if (mPtr.getClass().getCreatureStats(mPtr).isDead())
             return;
 
-        bool vampire
-            = mPtr.getClass().getCreatureStats(mPtr).getMagicEffects().get(ESM::MagicEffect::Vampirism).getMagnitude()
+        bool vampire = mPtr.getClass()
+                           .getCreatureStats(mPtr)
+                           .getMagicEffects()
+                           .getOrDefault(ESM::MagicEffect::Vampirism)
+                           .getMagnitude()
             > 0.0f;
         mAnimation->setVampire(vampire);
     }
@@ -2679,7 +2692,7 @@ namespace MWMechanics
             if (mPtr.getClass()
                     .getCreatureStats(mPtr)
                     .getMagicEffects()
-                    .get(ESM::MagicEffect::Invisibility)
+                    .getOrDefault(ESM::MagicEffect::Invisibility)
                     .getModifier()) // Ignore base magnitude (see bug #3555).
             {
                 if (mPtr == getPlayer())
@@ -2690,7 +2703,7 @@ namespace MWMechanics
             float chameleon = mPtr.getClass()
                                   .getCreatureStats(mPtr)
                                   .getMagicEffects()
-                                  .get(ESM::MagicEffect::Chameleon)
+                                  .getOrDefault(ESM::MagicEffect::Chameleon)
                                   .getMagnitude();
             if (chameleon)
             {
diff --git a/apps/openmw/mwmechanics/combat.cpp b/apps/openmw/mwmechanics/combat.cpp
index f835652561..917d06bea6 100644
--- a/apps/openmw/mwmechanics/combat.cpp
+++ b/apps/openmw/mwmechanics/combat.cpp
@@ -185,8 +185,8 @@ namespace MWMechanics
             return;
 
         const MWMechanics::MagicEffects& effects = actor.getClass().getCreatureStats(actor).getMagicEffects();
-        const float resistance = effects.get(ESM::MagicEffect::ResistNormalWeapons).getMagnitude() / 100.f;
-        const float weakness = effects.get(ESM::MagicEffect::WeaknessToNormalWeapons).getMagnitude() / 100.f;
+        const float resistance = effects.getOrDefault(ESM::MagicEffect::ResistNormalWeapons).getMagnitude() / 100.f;
+        const float weakness = effects.getOrDefault(ESM::MagicEffect::WeaknessToNormalWeapons).getMagnitude() / 100.f;
 
         damage *= 1.f - std::min(1.f, resistance - weakness);
 
@@ -313,15 +313,17 @@ namespace MWMechanics
             }
             static const float fCombatInvisoMult = gmst.find("fCombatInvisoMult")->mValue.getFloat();
             defenseTerm += std::min(100.f,
-                fCombatInvisoMult * victimStats.getMagicEffects().get(ESM::MagicEffect::Chameleon).getMagnitude());
+                fCombatInvisoMult
+                    * victimStats.getMagicEffects().getOrDefault(ESM::MagicEffect::Chameleon).getMagnitude());
             defenseTerm += std::min(100.f,
-                fCombatInvisoMult * victimStats.getMagicEffects().get(ESM::MagicEffect::Invisibility).getMagnitude());
+                fCombatInvisoMult
+                    * victimStats.getMagicEffects().getOrDefault(ESM::MagicEffect::Invisibility).getMagnitude());
         }
         float attackTerm = skillValue + (stats.getAttribute(ESM::Attribute::Agility).getModified() / 5.0f)
             + (stats.getAttribute(ESM::Attribute::Luck).getModified() / 10.0f);
         attackTerm *= stats.getFatigueTerm();
-        attackTerm += mageffects.get(ESM::MagicEffect::FortifyAttack).getMagnitude()
-            - mageffects.get(ESM::MagicEffect::Blind).getMagnitude();
+        attackTerm += mageffects.getOrDefault(ESM::MagicEffect::FortifyAttack).getMagnitude()
+            - mageffects.getOrDefault(ESM::MagicEffect::Blind).getMagnitude();
 
         return round(attackTerm - defenseTerm);
     }
@@ -338,7 +340,7 @@ namespace MWMechanics
             float magnitude = victim.getClass()
                                   .getCreatureStats(victim)
                                   .getMagicEffects()
-                                  .get(ESM::MagicEffect::FireShield + i)
+                                  .getOrDefault(ESM::MagicEffect::FireShield + i)
                                   .getMagnitude();
 
             if (!magnitude)
diff --git a/apps/openmw/mwmechanics/creaturestats.cpp b/apps/openmw/mwmechanics/creaturestats.cpp
index 0ef77f9f5c..44e1f4d2e1 100644
--- a/apps/openmw/mwmechanics/creaturestats.cpp
+++ b/apps/openmw/mwmechanics/creaturestats.cpp
@@ -225,8 +225,8 @@ namespace MWMechanics
 
     void CreatureStats::modifyMagicEffects(const MagicEffects& effects)
     {
-        bool recalc = effects.get(ESM::MagicEffect::FortifyMaximumMagicka).getModifier()
-            != mMagicEffects.get(ESM::MagicEffect::FortifyMaximumMagicka).getModifier();
+        bool recalc = effects.getOrDefault(ESM::MagicEffect::FortifyMaximumMagicka).getModifier()
+            != mMagicEffects.getOrDefault(ESM::MagicEffect::FortifyMaximumMagicka).getModifier();
         mMagicEffects.setModifiers(effects);
         if (recalc)
             recalculateMagicka();
@@ -246,7 +246,7 @@ namespace MWMechanics
 
     bool CreatureStats::isParalyzed() const
     {
-        return mMagicEffects.get(ESM::MagicEffect::Paralyze).getMagnitude() > 0;
+        return mMagicEffects.getOrDefault(ESM::MagicEffect::Paralyze).getMagnitude() > 0;
     }
 
     bool CreatureStats::isDead() const
@@ -359,7 +359,7 @@ namespace MWMechanics
         float evasion = (getAttribute(ESM::Attribute::Agility).getModified() / 5.0f)
             + (getAttribute(ESM::Attribute::Luck).getModified() / 10.0f);
         evasion *= getFatigueTerm();
-        evasion += std::min(100.f, mMagicEffects.get(ESM::MagicEffect::Sanctuary).getMagnitude());
+        evasion += std::min(100.f, mMagicEffects.getOrDefault(ESM::MagicEffect::Sanctuary).getMagnitude());
 
         return evasion;
     }
@@ -436,8 +436,8 @@ namespace MWMechanics
         else
             base = world->getStore().get<ESM::GameSetting>().find("fNPCbaseMagickaMult")->mValue.getFloat();
 
-        double magickaFactor
-            = base + mMagicEffects.get(EffectKey(ESM::MagicEffect::FortifyMaximumMagicka)).getMagnitude() * 0.1;
+        double magickaFactor = base
+            + mMagicEffects.getOrDefault(EffectKey(ESM::MagicEffect::FortifyMaximumMagicka)).getMagnitude() * 0.1;
 
         DynamicStat<float> magicka = getMagicka();
         float currentToBaseRatio = magicka.getBase() > 0 ? magicka.getCurrent() / magicka.getBase() : 0;
diff --git a/apps/openmw/mwmechanics/disease.hpp b/apps/openmw/mwmechanics/disease.hpp
index f4d2cc9067..c793d5d540 100644
--- a/apps/openmw/mwmechanics/disease.hpp
+++ b/apps/openmw/mwmechanics/disease.hpp
@@ -46,18 +46,18 @@ namespace MWMechanics
             if (Spells::hasCorprusEffect(spell))
                 resist = 1.f
                     - 0.01f
-                        * (actorEffects.get(ESM::MagicEffect::ResistCorprusDisease).getMagnitude()
-                            - actorEffects.get(ESM::MagicEffect::WeaknessToCorprusDisease).getMagnitude());
+                        * (actorEffects.getOrDefault(ESM::MagicEffect::ResistCorprusDisease).getMagnitude()
+                            - actorEffects.getOrDefault(ESM::MagicEffect::WeaknessToCorprusDisease).getMagnitude());
             else if (spell->mData.mType == ESM::Spell::ST_Disease)
                 resist = 1.f
                     - 0.01f
-                        * (actorEffects.get(ESM::MagicEffect::ResistCommonDisease).getMagnitude()
-                            - actorEffects.get(ESM::MagicEffect::WeaknessToCommonDisease).getMagnitude());
+                        * (actorEffects.getOrDefault(ESM::MagicEffect::ResistCommonDisease).getMagnitude()
+                            - actorEffects.getOrDefault(ESM::MagicEffect::WeaknessToCommonDisease).getMagnitude());
             else if (spell->mData.mType == ESM::Spell::ST_Blight)
                 resist = 1.f
                     - 0.01f
-                        * (actorEffects.get(ESM::MagicEffect::ResistBlightDisease).getMagnitude()
-                            - actorEffects.get(ESM::MagicEffect::WeaknessToBlightDisease).getMagnitude());
+                        * (actorEffects.getOrDefault(ESM::MagicEffect::ResistBlightDisease).getMagnitude()
+                            - actorEffects.getOrDefault(ESM::MagicEffect::WeaknessToBlightDisease).getMagnitude());
             else
                 continue;
 
diff --git a/apps/openmw/mwmechanics/magiceffects.cpp b/apps/openmw/mwmechanics/magiceffects.cpp
index d291d9798d..293d61c082 100644
--- a/apps/openmw/mwmechanics/magiceffects.cpp
+++ b/apps/openmw/mwmechanics/magiceffects.cpp
@@ -147,7 +147,7 @@ namespace MWMechanics
     {
         for (Collection::iterator it = mCollection.begin(); it != mCollection.end(); ++it)
         {
-            it->second.setModifier(effects.get(it->first).getModifier());
+            it->second.setModifier(effects.getOrDefault(it->first).getModifier());
         }
 
         for (Collection::const_iterator it = effects.begin(); it != effects.end(); ++it)
@@ -156,14 +156,14 @@ namespace MWMechanics
         }
     }
 
-    EffectParam MagicEffects::get(const EffectKey& key) const
+    EffectParam MagicEffects::getOrDefault(const EffectKey& key) const
     {
-        EffectParam param = EffectParam();
+        std::optional<EffectParam> param;
         get(key, param);
-        return param;
+        return param.value_or(EffectParam());
     }
 
-    bool MagicEffects::get(const EffectKey& key, EffectParam& param) const
+    bool MagicEffects::get(const EffectKey& key, std::optional<EffectParam>& param) const
     {
         Collection::const_iterator iter = mCollection.find(key);
 
@@ -268,7 +268,7 @@ namespace MWMechanics
 
         if (spellLine.empty())
         {
-            auto& effectIDStr = ESM::MagicEffect::effectIdToGmstString(effect.mIndex);
+            auto& effectIDStr = ESM::MagicEffect::indexToGmstString(effect.mIndex);
             spellLine = windowManager->getGameSettingString(effectIDStr, {});
         }
 
diff --git a/apps/openmw/mwmechanics/magiceffects.hpp b/apps/openmw/mwmechanics/magiceffects.hpp
index 4f3f3a1d48..b55bf54ff1 100644
--- a/apps/openmw/mwmechanics/magiceffects.hpp
+++ b/apps/openmw/mwmechanics/magiceffects.hpp
@@ -3,6 +3,7 @@
 
 #include <map>
 #include <string>
+#include <optional>
 
 namespace ESM
 {
@@ -104,8 +105,8 @@ namespace MWMechanics
         /// Copy Modifier values from \a effects, but keep original mBase values.
         void setModifiers(const MagicEffects& effects);
 
-        EffectParam get(const EffectKey& key) const;
-        bool get(const EffectKey& key, EffectParam& param) const;
+        EffectParam getOrDefault(const EffectKey& key) const;
+        bool get(const EffectKey& key, std::optional<EffectParam>& param) const;
         ///< This function can safely be used for keys that are not present.
 
         static MagicEffects diff(const MagicEffects& prev, const MagicEffects& now);
diff --git a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
index c8cc7ba32a..3268c01ecc 100644
--- a/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
+++ b/apps/openmw/mwmechanics/mechanicsmanagerimp.cpp
@@ -577,7 +577,11 @@ namespace MWMechanics
         if (playerStats.getDrawState() == MWMechanics::DrawState::Weapon)
             x += fDispWeaponDrawn;
 
-        x += ptr.getClass().getCreatureStats(ptr).getMagicEffects().get(ESM::MagicEffect::Charm).getMagnitude();
+        x += ptr.getClass()
+                 .getCreatureStats(ptr)
+                 .getMagicEffects()
+                 .getOrDefault(ESM::MagicEffect::Charm)
+                 .getMagnitude();
 
         if (clamp)
             return std::clamp<int>(x, 0, 100); //, normally clamped to [0..100] when used
@@ -1558,8 +1562,8 @@ namespace MWMechanics
         osg::Vec3f pos2(observer.getRefData().getPosition().asVec3());
         float distTerm = fSneakDistBase + fSneakDistMult * (pos1 - pos2).length();
 
-        float chameleon = stats.getMagicEffects().get(ESM::MagicEffect::Chameleon).getMagnitude();
-        float invisibility = stats.getMagicEffects().get(ESM::MagicEffect::Invisibility).getMagnitude();
+        float chameleon = stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Chameleon).getMagnitude();
+        float invisibility = stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Invisibility).getMagnitude();
         float x = sneakTerm * distTerm * stats.getFatigueTerm() + chameleon;
         if (invisibility > 0.f)
             x += 100.f;
@@ -1567,7 +1571,7 @@ namespace MWMechanics
         CreatureStats& observerStats = observer.getClass().getCreatureStats(observer);
         float obsAgility = observerStats.getAttribute(ESM::Attribute::Agility).getModified();
         float obsLuck = observerStats.getAttribute(ESM::Attribute::Luck).getModified();
-        float obsBlind = observerStats.getMagicEffects().get(ESM::MagicEffect::Blind).getMagnitude();
+        float obsBlind = observerStats.getMagicEffects().getOrDefault(ESM::MagicEffect::Blind).getMagnitude();
         float obsSneak = observer.getClass().getSkill(observer, ESM::Skill::Sneak);
 
         float obsTerm = obsSneak + 0.2f * obsAgility + 0.1f * obsLuck - obsBlind;
@@ -1755,14 +1759,14 @@ namespace MWMechanics
                 && ptr.getClass()
                         .getCreatureStats(ptr)
                         .getMagicEffects()
-                        .get(ESM::MagicEffect::CalmHumanoid)
+                        .getOrDefault(ESM::MagicEffect::CalmHumanoid)
                         .getMagnitude()
                     > 0)
             || (!ptr.getClass().isNpc()
                 && ptr.getClass()
                         .getCreatureStats(ptr)
                         .getMagicEffects()
-                        .get(ESM::MagicEffect::CalmCreature)
+                        .getOrDefault(ESM::MagicEffect::CalmCreature)
                         .getMagnitude()
                     > 0))
             return false;
diff --git a/apps/openmw/mwmechanics/spelleffects.cpp b/apps/openmw/mwmechanics/spelleffects.cpp
index 1ccb8f3396..3afe220a24 100644
--- a/apps/openmw/mwmechanics/spelleffects.cpp
+++ b/apps/openmw/mwmechanics/spelleffects.cpp
@@ -319,9 +319,9 @@ namespace
         {
             bool canReflect = !(magicEffect->mData.mFlags & ESM::MagicEffect::Unreflectable)
                 && !(effect.mFlags & ESM::ActiveEffect::Flag_Ignore_Reflect)
-                && magnitudes.get(ESM::MagicEffect::Reflect).getMagnitude() > 0.f && !caster.isEmpty();
+                && magnitudes.getOrDefault(ESM::MagicEffect::Reflect).getMagnitude() > 0.f && !caster.isEmpty();
             bool canAbsorb = !(effect.mFlags & ESM::ActiveEffect::Flag_Ignore_SpellAbsorption)
-                && magnitudes.get(ESM::MagicEffect::SpellAbsorption).getMagnitude() > 0.f;
+                && magnitudes.getOrDefault(ESM::MagicEffect::SpellAbsorption).getMagnitude() > 0.f;
             if (canReflect || canAbsorb)
             {
                 auto& prng = MWBase::Environment::get().getWorld()->getPrng();
@@ -561,7 +561,8 @@ namespace MWMechanics
                 {
                     const auto& magnitudes = target.getClass().getCreatureStats(target).getMagicEffects();
                     float volume = std::clamp(
-                        (magnitudes.get(effect.mEffectId).getModifier() + effect.mMagnitude) / 100.f, 0.f, 1.f);
+                        (magnitudes.getOrDefault(effect.mEffectId).getModifier() + effect.mMagnitude) / 100.f, 0.f,
+                        1.f);
                     MWBase::Environment::get().getSoundManager()->playSound3D(target,
                         ESM::RefId::stringRefId("magic sound"), volume, 1.f, MWSound::Type::Sfx,
                         MWSound::PlayMode::LoopNoEnv);
@@ -1058,7 +1059,7 @@ namespace MWMechanics
         {
             case ESM::MagicEffect::CommandCreature:
             case ESM::MagicEffect::CommandHumanoid:
-                if (magnitudes.get(effect.mEffectId).getMagnitude() <= 0.f)
+                if (magnitudes.getOrDefault(effect.mEffectId).getMagnitude() <= 0.f)
                 {
                     auto& seq = target.getClass().getCreatureStats(target).getAiSequence();
                     seq.erasePackageIf([&](const auto& package) {
@@ -1068,7 +1069,7 @@ namespace MWMechanics
                 }
                 break;
             case ESM::MagicEffect::ExtraSpell:
-                if (magnitudes.get(effect.mEffectId).getMagnitude() <= 0.f)
+                if (magnitudes.getOrDefault(effect.mEffectId).getMagnitude() <= 0.f)
                     target.getClass().getInventoryStore(target).autoEquip();
                 break;
             case ESM::MagicEffect::TurnUndead:
@@ -1096,7 +1097,7 @@ namespace MWMechanics
                 break;
             case ESM::MagicEffect::NightEye:
             {
-                const MWMechanics::EffectParam nightEye = magnitudes.get(effect.mEffectId);
+                const MWMechanics::EffectParam nightEye = magnitudes.getOrDefault(effect.mEffectId);
                 if (nightEye.getMagnitude() < 0.f && nightEye.getBase() < 0)
                 {
                     // The PCVisionBonus functions are different from every other magic effect function in that they
@@ -1115,7 +1116,7 @@ namespace MWMechanics
                     target, effect, ESM::MagicEffect::RallyCreature, AiSetting::Flee, effect.mMagnitude, invalid);
                 break;
             case ESM::MagicEffect::Sound:
-                if (magnitudes.get(effect.mEffectId).getModifier() <= 0.f && target == getPlayer())
+                if (magnitudes.getOrDefault(effect.mEffectId).getModifier() <= 0.f && target == getPlayer())
                     MWBase::Environment::get().getSoundManager()->stopSound3D(
                         target, ESM::RefId::stringRefId("magic sound"));
                 break;
@@ -1275,7 +1276,7 @@ namespace MWMechanics
         auto& magnitudes = target.getClass().getCreatureStats(target).getMagicEffects();
         magnitudes.add(EffectKey(effect.mEffectId, effect.mArg), EffectParam(-effect.mMagnitude));
         removeMagicEffect(target, spellParams, effect);
-        if (magnitudes.get(effect.mEffectId).getMagnitude() <= 0.f)
+        if (magnitudes.getOrDefault(effect.mEffectId).getMagnitude() <= 0.f)
         {
             auto anim = MWBase::Environment::get().getWorld()->getAnimation(target);
             if (anim)
diff --git a/apps/openmw/mwmechanics/spellpriority.cpp b/apps/openmw/mwmechanics/spellpriority.cpp
index e491332bfd..4e813ec37c 100644
--- a/apps/openmw/mwmechanics/spellpriority.cpp
+++ b/apps/openmw/mwmechanics/spellpriority.cpp
@@ -265,7 +265,7 @@ namespace MWMechanics
                 const CreatureStats& stats = enemy.getClass().getCreatureStats(enemy);
 
                 // Enemy can't cast spells
-                if (stats.getMagicEffects().get(ESM::MagicEffect::Silence).getMagnitude() > 0)
+                if (stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Silence).getMagnitude() > 0)
                     return 0.f;
 
                 if (stats.isParalyzed() || stats.getKnockedDown())
@@ -596,7 +596,7 @@ namespace MWMechanics
             if (effect.mEffectID <= ESM::MagicEffect::BoundLongbow)
             {
                 for (int e = ESM::MagicEffect::BoundDagger; e <= ESM::MagicEffect::BoundLongbow; ++e)
-                    if (actor.getClass().getCreatureStats(actor).getMagicEffects().get(e).getMagnitude() > 0.f
+                    if (actor.getClass().getCreatureStats(actor).getMagicEffects().getOrDefault(e).getMagnitude() > 0.f
                         && (e != ESM::MagicEffect::BoundLongbow || effect.mEffectID == e
                             || rateAmmo(actor, enemy, getWeaponType(ESM::Weapon::MarksmanBow)->mAmmoType) <= 0.f))
                         return 0.f;
@@ -619,7 +619,11 @@ namespace MWMechanics
                 // Prefer summoning items we know how to use
                 rating *= (50.f + actor.getClass().getSkill(actor, skill)) / 100.f;
             }
-            else if (actor.getClass().getCreatureStats(actor).getMagicEffects().get(effect.mEffectID).getMagnitude()
+            else if (actor.getClass()
+                         .getCreatureStats(actor)
+                         .getMagicEffects()
+                         .getOrDefault(effect.mEffectID)
+                         .getMagnitude()
                 > 0.f)
                 return 0.f;
         }
@@ -662,14 +666,14 @@ namespace MWMechanics
             {
                 CreatureStats& stats = enemy.getClass().getCreatureStats(enemy);
 
-                if (stats.getMagicEffects().get(effect.mEffectID).getMagnitude() > 0)
+                if (stats.getMagicEffects().getOrDefault(effect.mEffectID).getMagnitude() > 0)
                     return 0.f;
             }
             else
             {
                 CreatureStats& stats = actor.getClass().getCreatureStats(actor);
 
-                if (stats.getMagicEffects().get(effect.mEffectID).getMagnitude() > 0)
+                if (stats.getMagicEffects().getOrDefault(effect.mEffectID).getMagnitude() > 0)
                     return 0.f;
             }
         }
diff --git a/apps/openmw/mwmechanics/spellresistance.cpp b/apps/openmw/mwmechanics/spellresistance.cpp
index 0fb864aa8a..e55d851ec6 100644
--- a/apps/openmw/mwmechanics/spellresistance.cpp
+++ b/apps/openmw/mwmechanics/spellresistance.cpp
@@ -79,16 +79,16 @@ namespace MWMechanics
 
         float resistance = 0;
         if (resistanceEffect != -1)
-            resistance += actorEffects->get(resistanceEffect).getMagnitude();
+            resistance += actorEffects->getOrDefault(resistanceEffect).getMagnitude();
         if (weaknessEffect != -1)
-            resistance -= actorEffects->get(weaknessEffect).getMagnitude();
+            resistance -= actorEffects->getOrDefault(weaknessEffect).getMagnitude();
 
         if (effectId == ESM::MagicEffect::FireDamage)
-            resistance += actorEffects->get(ESM::MagicEffect::FireShield).getMagnitude();
+            resistance += actorEffects->getOrDefault(ESM::MagicEffect::FireShield).getMagnitude();
         if (effectId == ESM::MagicEffect::ShockDamage)
-            resistance += actorEffects->get(ESM::MagicEffect::LightningShield).getMagnitude();
+            resistance += actorEffects->getOrDefault(ESM::MagicEffect::LightningShield).getMagnitude();
         if (effectId == ESM::MagicEffect::FrostDamage)
-            resistance += actorEffects->get(ESM::MagicEffect::FrostShield).getMagnitude();
+            resistance += actorEffects->getOrDefault(ESM::MagicEffect::FrostShield).getMagnitude();
 
         return resistance;
     }
diff --git a/apps/openmw/mwmechanics/spellutil.cpp b/apps/openmw/mwmechanics/spellutil.cpp
index 344597bca0..60574880a1 100644
--- a/apps/openmw/mwmechanics/spellutil.cpp
+++ b/apps/openmw/mwmechanics/spellutil.cpp
@@ -151,7 +151,7 @@ namespace MWMechanics
 
         CreatureStats& stats = actor.getClass().getCreatureStats(actor);
 
-        if (stats.getMagicEffects().get(ESM::MagicEffect::Silence).getMagnitude() && !godmode)
+        if (stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Silence).getMagnitude() && !godmode)
             return 0;
 
         if (spell->mData.mType == ESM::Spell::ST_Power)
@@ -169,7 +169,7 @@ namespace MWMechanics
         if (spell->mData.mFlags & ESM::Spell::F_Always)
             return 100;
 
-        float castBonus = -stats.getMagicEffects().get(ESM::MagicEffect::Sound).getMagnitude();
+        float castBonus = -stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Sound).getMagnitude();
         float castChance = baseChance + castBonus;
         castChance *= stats.getFatigueTerm();
 
diff --git a/apps/openmw/mwphysics/physicssystem.cpp b/apps/openmw/mwphysics/physicssystem.cpp
index 1c37ac029e..d1f13326cb 100644
--- a/apps/openmw/mwphysics/physicssystem.cpp
+++ b/apps/openmw/mwphysics/physicssystem.cpp
@@ -666,7 +666,7 @@ namespace MWPhysics
 
         // check if Actor should spawn above water
         const MWMechanics::MagicEffects& effects = ptr.getClass().getCreatureStats(ptr).getMagicEffects();
-        const bool canWaterWalk = effects.get(ESM::MagicEffect::WaterWalking).getMagnitude() > 0;
+        const bool canWaterWalk = effects.getOrDefault(ESM::MagicEffect::WaterWalking).getMagnitude() > 0;
 
         auto actor = std::make_shared<Actor>(ptr, shape, mTaskScheduler.get(), canWaterWalk, mActorCollisionShapeType);
 
@@ -750,7 +750,7 @@ namespace MWPhysics
             const MWMechanics::MagicEffects& effects = stats.getMagicEffects();
 
             bool waterCollision = false;
-            if (cell->getCell()->hasWater() && effects.get(ESM::MagicEffect::WaterWalking).getMagnitude())
+            if (cell->getCell()->hasWater() && effects.getOrDefault(ESM::MagicEffect::WaterWalking).getMagnitude())
             {
                 if (physicActor->getCollisionMode()
                     || !world->isUnderwater(ptr.getCell(), ptr.getRefData().getPosition().asVec3()))
@@ -761,10 +761,10 @@ namespace MWPhysics
 
             // Slow fall reduces fall speed by a factor of (effect magnitude / 200)
             const float slowFall
-                = 1.f - std::clamp(effects.get(ESM::MagicEffect::SlowFall).getMagnitude() * 0.005f, 0.f, 1.f);
+                = 1.f - std::clamp(effects.getOrDefault(ESM::MagicEffect::SlowFall).getMagnitude() * 0.005f, 0.f, 1.f);
             const bool godmode = ptr == world->getPlayerConstPtr() && world->getGodModeState();
             const bool inert = stats.isDead()
-                || (!godmode && stats.getMagicEffects().get(ESM::MagicEffect::Paralyze).getModifier() > 0);
+                || (!godmode && stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Paralyze).getModifier() > 0);
 
             simulations.emplace_back(ActorSimulation{
                 physicActor, ActorFrameData{ *physicActor, inert, waterCollision, slowFall, waterlevel } });
diff --git a/apps/openmw/mwrender/npcanimation.cpp b/apps/openmw/mwrender/npcanimation.cpp
index 14558e8047..43769c7ef1 100644
--- a/apps/openmw/mwrender/npcanimation.cpp
+++ b/apps/openmw/mwrender/npcanimation.cpp
@@ -222,7 +222,7 @@ namespace MWRender
     {
         const MWWorld::Class& cls = ptr.getClass();
         NpcAnimation::NpcType curType = Type_Normal;
-        if (cls.getCreatureStats(ptr).getMagicEffects().get(ESM::MagicEffect::Vampirism).getMagnitude() > 0)
+        if (cls.getCreatureStats(ptr).getMagicEffects().getOrDefault(ESM::MagicEffect::Vampirism).getMagnitude() > 0)
             curType = Type_Vampire;
         if (cls.getNpcStats(ptr).isWerewolf())
             curType = Type_Werewolf;
diff --git a/apps/openmw/mwscript/miscextensions.cpp b/apps/openmw/mwscript/miscextensions.cpp
index 2d4d5d045a..7787c15ad3 100644
--- a/apps/openmw/mwscript/miscextensions.cpp
+++ b/apps/openmw/mwscript/miscextensions.cpp
@@ -582,7 +582,7 @@ namespace MWScript
                     k.has_value() && *k >= 0 && *k <= 32767)
                     key = *k;
                 else
-                    key = ESM::MagicEffect::effectGmstIdToId(effect);
+                    key = ESM::MagicEffect::effectGmstIdToIndex(effect);
 
                 const MWMechanics::CreatureStats& stats = ptr.getClass().getCreatureStats(ptr);
 
diff --git a/apps/openmw/mwscript/statsextensions.cpp b/apps/openmw/mwscript/statsextensions.cpp
index 1b2fe0275f..877fa79099 100644
--- a/apps/openmw/mwscript/statsextensions.cpp
+++ b/apps/openmw/mwscript/statsextensions.cpp
@@ -1193,17 +1193,17 @@ namespace MWScript
                 MWWorld::Ptr ptr = R()(runtime);
 
                 const MWMechanics::MagicEffects& effects = ptr.getClass().getCreatureStats(ptr).getMagicEffects();
-                float currentValue = effects.get(mPositiveEffect).getMagnitude();
+                float currentValue = effects.getOrDefault(mPositiveEffect).getMagnitude();
                 if (mNegativeEffect != -1)
-                    currentValue -= effects.get(mNegativeEffect).getMagnitude();
+                    currentValue -= effects.getOrDefault(mNegativeEffect).getMagnitude();
 
                 // GetResist* should take in account elemental shields
                 if (mPositiveEffect == ESM::MagicEffect::ResistFire)
-                    currentValue += effects.get(ESM::MagicEffect::FireShield).getMagnitude();
+                    currentValue += effects.getOrDefault(ESM::MagicEffect::FireShield).getMagnitude();
                 if (mPositiveEffect == ESM::MagicEffect::ResistShock)
-                    currentValue += effects.get(ESM::MagicEffect::LightningShield).getMagnitude();
+                    currentValue += effects.getOrDefault(ESM::MagicEffect::LightningShield).getMagnitude();
                 if (mPositiveEffect == ESM::MagicEffect::ResistFrost)
-                    currentValue += effects.get(ESM::MagicEffect::FrostShield).getMagnitude();
+                    currentValue += effects.getOrDefault(ESM::MagicEffect::FrostShield).getMagnitude();
 
                 int ret = static_cast<int>(currentValue);
                 runtime.push(ret);
@@ -1227,17 +1227,17 @@ namespace MWScript
             {
                 MWWorld::Ptr ptr = R()(runtime);
                 MWMechanics::MagicEffects& effects = ptr.getClass().getCreatureStats(ptr).getMagicEffects();
-                float currentValue = effects.get(mPositiveEffect).getMagnitude();
+                float currentValue = effects.getOrDefault(mPositiveEffect).getMagnitude();
                 if (mNegativeEffect != -1)
-                    currentValue -= effects.get(mNegativeEffect).getMagnitude();
+                    currentValue -= effects.getOrDefault(mNegativeEffect).getMagnitude();
 
                 // SetResist* should take in account elemental shields
                 if (mPositiveEffect == ESM::MagicEffect::ResistFire)
-                    currentValue += effects.get(ESM::MagicEffect::FireShield).getMagnitude();
+                    currentValue += effects.getOrDefault(ESM::MagicEffect::FireShield).getMagnitude();
                 if (mPositiveEffect == ESM::MagicEffect::ResistShock)
-                    currentValue += effects.get(ESM::MagicEffect::LightningShield).getMagnitude();
+                    currentValue += effects.getOrDefault(ESM::MagicEffect::LightningShield).getMagnitude();
                 if (mPositiveEffect == ESM::MagicEffect::ResistFrost)
-                    currentValue += effects.get(ESM::MagicEffect::FrostShield).getMagnitude();
+                    currentValue += effects.getOrDefault(ESM::MagicEffect::FrostShield).getMagnitude();
 
                 int arg = runtime[0].mInteger;
                 runtime.pop();
@@ -1276,7 +1276,8 @@ namespace MWScript
             {
                 MWWorld::Ptr player = MWMechanics::getPlayer();
                 MWMechanics::EffectParam nightEye
-                    = player.getClass().getCreatureStats(player).getMagicEffects().get(ESM::MagicEffect::NightEye);
+                    = player.getClass().getCreatureStats(player).getMagicEffects().getOrDefault(
+                        ESM::MagicEffect::NightEye);
                 runtime.push(std::clamp(nightEye.getMagnitude() / 100.f, 0.f, 1.f));
             }
         };
@@ -1290,8 +1291,8 @@ namespace MWScript
                 runtime.pop();
                 MWWorld::Ptr player = MWMechanics::getPlayer();
                 auto& effects = player.getClass().getCreatureStats(player).getMagicEffects();
-                float delta
-                    = std::clamp(arg * 100.f, 0.f, 100.f) - effects.get(ESM::MagicEffect::NightEye).getMagnitude();
+                float delta = std::clamp(arg * 100.f, 0.f, 100.f)
+                    - effects.getOrDefault(ESM::MagicEffect::NightEye).getMagnitude();
                 effects.modifyBase(ESM::MagicEffect::NightEye, static_cast<int>(delta));
             }
         };
@@ -1305,7 +1306,7 @@ namespace MWScript
                 runtime.pop();
                 MWWorld::Ptr player = MWMechanics::getPlayer();
                 auto& effects = player.getClass().getCreatureStats(player).getMagicEffects();
-                const MWMechanics::EffectParam nightEye = effects.get(ESM::MagicEffect::NightEye);
+                const MWMechanics::EffectParam nightEye = effects.getOrDefault(ESM::MagicEffect::NightEye);
                 float newBase = std::clamp(nightEye.getMagnitude() + arg * 100.f, 0.f, 100.f);
                 newBase -= nightEye.getModifier();
                 float delta = std::clamp(newBase, 0.f, 100.f) - nightEye.getMagnitude();
diff --git a/apps/openmw/mwworld/esmstore.cpp b/apps/openmw/mwworld/esmstore.cpp
index 915a6b5a4b..3041c7cb5a 100644
--- a/apps/openmw/mwworld/esmstore.cpp
+++ b/apps/openmw/mwworld/esmstore.cpp
@@ -538,8 +538,8 @@ namespace MWWorld
                     {
                         iter->mAttribute = -1;
                         Log(Debug::Verbose)
-                            << ESM::MagicEffect::effectIdToGmstString(iter->mEffectID) << " effect of spell '"
-                            << spell.mId << "' has an attribute argument present. Dropping the argument.";
+                            << ESM::MagicEffect::indexToGmstString(iter->mEffectID) << " effect of spell '" << spell.mId
+                            << "' has an attribute argument present. Dropping the argument.";
                         changed = true;
                     }
                 }
@@ -549,8 +549,8 @@ namespace MWWorld
                     {
                         iter->mSkill = -1;
                         Log(Debug::Verbose)
-                            << ESM::MagicEffect::effectIdToGmstString(iter->mEffectID) << " effect of spell '"
-                            << spell.mId << "' has a skill argument present. Dropping the argument.";
+                            << ESM::MagicEffect::indexToGmstString(iter->mEffectID) << " effect of spell '" << spell.mId
+                            << "' has a skill argument present. Dropping the argument.";
                         changed = true;
                     }
                 }
@@ -558,9 +558,8 @@ namespace MWWorld
                 {
                     iter->mSkill = -1;
                     iter->mAttribute = -1;
-                    Log(Debug::Verbose) << ESM::MagicEffect::effectIdToGmstString(iter->mEffectID)
-                                        << " effect of spell '" << spell.mId
-                                        << "' has argument(s) present. Dropping the argument(s).";
+                    Log(Debug::Verbose) << ESM::MagicEffect::indexToGmstString(iter->mEffectID) << " effect of spell '"
+                                        << spell.mId << "' has argument(s) present. Dropping the argument(s).";
                     changed = true;
                 }
 
diff --git a/apps/openmw/mwworld/player.cpp b/apps/openmw/mwworld/player.cpp
index 00a0ee7aa6..38eb728268 100644
--- a/apps/openmw/mwworld/player.cpp
+++ b/apps/openmw/mwworld/player.cpp
@@ -503,10 +503,10 @@ namespace MWWorld
         int blind = 0;
         const auto& magicEffects = playerClass.getCreatureStats(player).getMagicEffects();
         if (!world->getGodModeState())
-            blind = static_cast<int>(magicEffects.get(ESM::MagicEffect::Blind).getModifier());
+            blind = static_cast<int>(magicEffects.getOrDefault(ESM::MagicEffect::Blind).getModifier());
         windowMgr->setBlindness(std::clamp(blind, 0, 100));
 
-        int nightEye = static_cast<int>(magicEffects.get(ESM::MagicEffect::NightEye).getMagnitude());
+        int nightEye = static_cast<int>(magicEffects.getOrDefault(ESM::MagicEffect::NightEye).getMagnitude());
         rendering->setNightEyeFactor(std::min(1.f, (nightEye / 100.f)));
     }
 
diff --git a/apps/openmw/mwworld/worldimp.cpp b/apps/openmw/mwworld/worldimp.cpp
index 1f130a6b45..8d8eccf17b 100644
--- a/apps/openmw/mwworld/worldimp.cpp
+++ b/apps/openmw/mwworld/worldimp.cpp
@@ -2137,13 +2137,15 @@ namespace MWWorld
             return false;
 
         const bool isPlayer = ptr == getPlayerConstPtr();
-        if (!(isPlayer && mGodMode) && stats.getMagicEffects().get(ESM::MagicEffect::Paralyze).getModifier() > 0)
+        if (!(isPlayer && mGodMode)
+            && stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Paralyze).getModifier() > 0)
             return false;
 
         if (ptr.getClass().canFly(ptr))
             return true;
 
-        if (stats.getMagicEffects().get(ESM::MagicEffect::Levitate).getMagnitude() > 0 && isLevitationEnabled())
+        if (stats.getMagicEffects().getOrDefault(ESM::MagicEffect::Levitate).getMagnitude() > 0
+            && isLevitationEnabled())
             return true;
 
         const MWPhysics::Actor* actor = mPhysics->getActor(ptr);
@@ -2159,7 +2161,7 @@ namespace MWWorld
             return false;
 
         const MWMechanics::CreatureStats& stats = ptr.getClass().getCreatureStats(ptr);
-        if (stats.getMagicEffects().get(ESM::MagicEffect::SlowFall).getMagnitude() > 0)
+        if (stats.getMagicEffects().getOrDefault(ESM::MagicEffect::SlowFall).getMagnitude() > 0)
             return true;
 
         return false;
@@ -3446,11 +3448,11 @@ namespace MWWorld
         const MWMechanics::MagicEffects& effects = ptr.getClass().getCreatureStats(ptr).getMagicEffects();
         float dist = 0;
         if (type == World::Detect_Creature)
-            dist = effects.get(ESM::MagicEffect::DetectAnimal).getMagnitude();
+            dist = effects.getOrDefault(ESM::MagicEffect::DetectAnimal).getMagnitude();
         else if (type == World::Detect_Key)
-            dist = effects.get(ESM::MagicEffect::DetectKey).getMagnitude();
+            dist = effects.getOrDefault(ESM::MagicEffect::DetectKey).getMagnitude();
         else if (type == World::Detect_Enchantment)
-            dist = effects.get(ESM::MagicEffect::DetectEnchantment).getMagnitude();
+            dist = effects.getOrDefault(ESM::MagicEffect::DetectEnchantment).getMagnitude();
 
         if (!dist)
             return;
@@ -3478,7 +3480,7 @@ namespace MWWorld
                                           .getClass()
                                           .getCreatureStats(mPlayer->getPlayer())
                                           .getMagicEffects()
-                                          .get(ESM::MagicEffect::Telekinesis)
+                                          .getOrDefault(ESM::MagicEffect::Telekinesis)
                                           .getMagnitude();
         telekinesisRangeBonus = feetToGameUnits(telekinesisRangeBonus);
 
diff --git a/components/esm3/loadmgef.cpp b/components/esm3/loadmgef.cpp
index 3a12c69ea1..ee5b48038f 100644
--- a/components/esm3/loadmgef.cpp
+++ b/components/esm3/loadmgef.cpp
@@ -24,156 +24,6 @@ namespace ESM
             0x1048, 0x1048, 0x1048, 0x1048 };
     }
 
-    const std::string_view MagicEffect::sIndexNames[MagicEffect::Length] = {
-        "WaterBreathing",
-        "SwiftSwim",
-        "WaterWalking",
-        "Shield",
-        "FireShield",
-        "LightningShield",
-        "FrostShield",
-        "Burden",
-        "Feather",
-        "Jump",
-        "Levitate",
-        "SlowFall",
-        "Lock",
-        "Open",
-        "FireDamage",
-        "ShockDamage",
-        "FrostDamage",
-        "DrainAttribute",
-        "DrainHealth",
-        "DrainMagicka",
-        "DrainFatigue",
-        "DrainSkill",
-        "DamageAttribute",
-        "DamageHealth",
-        "DamageMagicka",
-        "DamageFatigue",
-        "DamageSkill",
-        "Poison",
-        "WeaknessToFire",
-        "WeaknessToFrost",
-        "WeaknessToShock",
-        "WeaknessToMagicka",
-        "WeaknessToCommonDisease",
-        "WeaknessToBlightDisease",
-        "WeaknessToCorprusDisease",
-        "WeaknessToPoison",
-        "WeaknessToNormalWeapons",
-        "DisintegrateWeapon",
-        "DisintegrateArmor",
-        "Invisibility",
-        "Chameleon",
-        "Light",
-        "Sanctuary",
-        "NightEye",
-        "Charm",
-        "Paralyze",
-        "Silence",
-        "Blind",
-        "Sound",
-        "CalmHumanoid",
-        "CalmCreature",
-        "FrenzyHumanoid",
-        "FrenzyCreature",
-        "DemoralizeHumanoid",
-        "DemoralizeCreature",
-        "RallyHumanoid",
-        "RallyCreature",
-        "Dispel",
-        "Soultrap",
-        "Telekinesis",
-        "Mark",
-        "Recall",
-        "DivineIntervention",
-        "AlmsiviIntervention",
-        "DetectAnimal",
-        "DetectEnchantment",
-        "DetectKey",
-        "SpellAbsorption",
-        "Reflect",
-        "CureCommonDisease",
-        "CureBlightDisease",
-        "CureCorprusDisease",
-        "CurePoison",
-        "CureParalyzation",
-        "RestoreAttribute",
-        "RestoreHealth",
-        "RestoreMagicka",
-        "RestoreFatigue",
-        "RestoreSkill",
-        "FortifyAttribute",
-        "FortifyHealth",
-        "FortifyMagicka",
-        "FortifyFatigue",
-        "FortifySkill",
-        "FortifyMaximumMagicka",
-        "AbsorbAttribute",
-        "AbsorbHealth",
-        "AbsorbMagicka",
-        "AbsorbFatigue",
-        "AbsorbSkill",
-        "ResistFire",
-        "ResistFrost",
-        "ResistShock",
-        "ResistMagicka",
-        "ResistCommonDisease",
-        "ResistBlightDisease",
-        "ResistCorprusDisease",
-        "ResistPoison",
-        "ResistNormalWeapons",
-        "ResistParalysis",
-        "RemoveCurse",
-        "TurnUndead",
-        "SummonScamp",
-        "SummonClannfear",
-        "SummonDaedroth",
-        "SummonDremora",
-        "SummonAncestralGhost",
-        "SummonSkeletalMinion",
-        "SummonBonewalker",
-        "SummonGreaterBonewalker",
-        "SummonBonelord",
-        "SummonWingedTwilight",
-        "SummonHunger",
-        "SummonGoldenSaint",
-        "SummonFlameAtronach",
-        "SummonFrostAtronach",
-        "SummonStormAtronach",
-        "FortifyAttack",
-        "CommandCreature",
-        "CommandHumanoid",
-        "BoundDagger",
-        "BoundLongsword",
-        "BoundMace",
-        "BoundBattleAxe",
-        "BoundSpear",
-        "BoundLongbow",
-        "ExtraSpell",
-        "BoundCuirass",
-        "BoundHelm",
-        "BoundBoots",
-        "BoundShield",
-        "BoundGloves",
-        "Corprus",
-        "Vampirism",
-        "SummonCenturionSphere",
-        "SunDamage",
-        "StuntedMagicka",
-
-        // Tribunal only
-        "SummonFabricant",
-
-        // Bloodmoon only
-        "SummonWolf",
-        "SummonBear",
-        "SummonBonewolf",
-        "SummonCreature04",
-        "SummonCreature05",
-    };
-
     void MagicEffect::load(ESMReader& esm, bool& isDeleted)
     {
         isDeleted = false; // MagicEffect record can't be deleted now (may be changed in the future)
@@ -504,7 +354,7 @@ namespace ESM
     };
 
     // Map effect ID to identifying name
-    const std::array<std::string, MagicEffect::Length> MagicEffect::sEffectNames = {
+    const std::array<std::string_view, MagicEffect::Length> MagicEffect::sIndexNames = {
         "WaterBreathing",
         "SwiftSwim",
         "WaterWalking",
@@ -654,21 +504,21 @@ namespace ESM
         "SummonCreature05",
     };
 
-    static std::map<std::string_view, int, Misc::StringUtils::CiComp> initStringToIntMap(
-        const std::array<std::string, MagicEffect::Length>& strings)
+    template <typename Collection>
+    static std::map<std::string_view, int, Misc::StringUtils::CiComp> initStringToIntMap(const Collection& strings)
     {
         std::map<std::string_view, int, Misc::StringUtils::CiComp> map;
-        for (int i = 0; i < (int)strings.size(); i++)
+        for (size_t i = 0; i < strings.size(); i++)
             map[strings[i]] = i;
 
         return map;
     }
 
-    const std::map<std::string_view, int, Misc::StringUtils::CiComp> MagicEffect::sGmstEffectIdToEffectIdMap
+    const std::map<std::string_view, int, Misc::StringUtils::CiComp> MagicEffect::sGmstEffectIdToIndexMap
         = initStringToIntMap(MagicEffect::sGmstEffectIds);
 
-    const std::map<std::string_view, int, Misc::StringUtils::CiComp> MagicEffect::sEffectNameToEffectIdMap
-        = initStringToIntMap(MagicEffect::sEffectNames);
+    const std::map<std::string_view, int, Misc::StringUtils::CiComp> MagicEffect::sIndexNameToIndexMap
+        = initStringToIntMap(MagicEffect::sIndexNames);
 
     class FindSecond
     {
@@ -729,35 +579,35 @@ namespace ESM
         mDescription.clear();
     }
 
-    const std::string& MagicEffect::effectIdToGmstString(int effectID)
+    const std::string& MagicEffect::indexToGmstString(int effectID)
     {
-        if (effectID >= (int)sGmstEffectIds.size() || effectID < 0)
+        if (effectID < 0 || static_cast<std::size_t>(effectID) >= sGmstEffectIds.size())
             throw std::runtime_error(std::string("Unimplemented effect ID ") + std::to_string(effectID));
 
         return sGmstEffectIds[effectID];
     }
 
-    const std::string& MagicEffect::effectIdToName(int effectID)
+    std::string_view MagicEffect::indexToName(int effectID)
     {
-        if (effectID >= (int)sEffectNames.size() || effectID < 0)
+        if (effectID < 0 || static_cast<std::size_t>(effectID) >= sIndexNames.size())
             throw std::runtime_error(std::string("Unimplemented effect ID ") + std::to_string(effectID));
 
-        return sEffectNames[effectID];
+        return sIndexNames[effectID];
     }
 
-    int MagicEffect::effectNameToId(std::string_view effect)
+    int MagicEffect::indexNameToIndex(std::string_view effect)
     {
-        auto name = sEffectNameToEffectIdMap.find(effect);
-        if (name == sEffectNameToEffectIdMap.end())
+        auto name = sIndexNameToIndexMap.find(effect);
+        if (name == sIndexNameToIndexMap.end())
             throw std::runtime_error("Unimplemented effect " + std::string(effect));
 
         return name->second;
     }
 
-    int MagicEffect::effectGmstIdToId(std::string_view gmstId)
+    int MagicEffect::effectGmstIdToIndex(std::string_view gmstId)
     {
-        auto name = sGmstEffectIdToEffectIdMap.find(gmstId);
-        if (name == sGmstEffectIdToEffectIdMap.end())
+        auto name = sGmstEffectIdToIndexMap.find(gmstId);
+        if (name == sGmstEffectIdToIndexMap.end())
             throw std::runtime_error("Unimplemented effect " + std::string(gmstId));
 
         return name->second;
diff --git a/components/esm3/loadmgef.hpp b/components/esm3/loadmgef.hpp
index eead3a7015..1de3fb8a0a 100644
--- a/components/esm3/loadmgef.hpp
+++ b/components/esm3/loadmgef.hpp
@@ -267,16 +267,14 @@ namespace ESM
         };
 
         static const std::array<std::string, Length> sGmstEffectIds;
-        static const std::array<std::string, Length> sEffectNames;
-        static const std::map<std::string_view, int, Misc::StringUtils::CiComp> sGmstEffectIdToEffectIdMap;
-        static const std::map<std::string_view, int, Misc::StringUtils::CiComp> sEffectNameToEffectIdMap;
+        static const std::array<std::string_view, Length> sIndexNames;
+        static const std::map<std::string_view, int, Misc::StringUtils::CiComp> sGmstEffectIdToIndexMap;
+        static const std::map<std::string_view, int, Misc::StringUtils::CiComp> sIndexNameToIndexMap;
 
-        static const std::string& effectIdToGmstString(int effectID);
-        static const std::string& effectIdToName(int effectID);
-        static int effectNameToId(std::string_view effect);
-        static int effectGmstIdToId(std::string_view gmstId);
-
-        static const std::string_view sIndexNames[MagicEffect::Length];
+        static const std::string& indexToGmstString(int effectID);
+        static std::string_view indexToName(int effectID);
+        static int indexNameToIndex(std::string_view effect);
+        static int effectGmstIdToIndex(std::string_view gmstId);
 
         static RefId indexToRefId(int index);
     };