Apply disease resistance manually as according to wiki

apps/openmw/mwmechanics/spellcasting.cpp

@@ -35,6 +35,23 @@ namespace MWMechanics
         if (!found)
             return;
 
+        const ESM::Spell* spell = MWBase::Environment::get().getWorld()->getStore().get<ESM::Spell>().search (mId);
+        if (spell && (spell->mData.mType == ESM::Spell::ST_Disease || spell->mData.mType == ESM::Spell::ST_Blight))
+        {
+            float x = (spell->mData.mType == ESM::Spell::ST_Disease) ?
+                        target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::ResistCommonDisease).mMagnitude
+                      : target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::ResistBlightDisease).mMagnitude;
+
+            int roll = std::rand()/ (static_cast<double> (RAND_MAX) + 1) * 100; // [0, 99]
+            if (roll <= x)
+            {
+                // Fully resisted, show message
+                if (target.getRefData().getHandle() == "player")
+                    MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicPCResisted}");
+                return;
+            }
+        }
+
         ESM::EffectList reflectedEffects;
         std::vector<ActiveSpells::Effect> appliedLastingEffects;
         bool firstAppliedEffect = true;
@@ -59,7 +76,6 @@ namespace MWMechanics
                 // Try absorbing if it's a spell
                 // NOTE: Vanilla does this once per effect source instead of adding the % from all sources together, not sure
                 // if that is worth replicating.
-                const ESM::Spell* spell = MWBase::Environment::get().getWorld()->getStore().get<ESM::Spell>().search (mId);
                 if (spell && caster != target)
                 {
                     int absorb = target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::SpellAbsorption).mMagnitude;
@@ -97,35 +113,15 @@ namespace MWMechanics
                 // Try resisting
                 if (magnitudeMult > 0 && target.getClass().isActor())
                 {
-                    const ESM::Spell *spell =
-                            MWBase::Environment::get().getWorld()->getStore().get<ESM::Spell>().search (mId);
 
-                    if (spell->mData.mType == ESM::Spell::ST_Disease || spell->mData.mType == ESM::Spell::ST_Blight)
+                    magnitudeMult = MWMechanics::getEffectMultiplier(effectIt->mEffectID, target, caster, spell);
+                    if (magnitudeMult == 0)
                     {
-                        float x = (spell->mData.mType == ESM::Spell::ST_Disease) ?
-                                    target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::ResistCommonDisease).mMagnitude
-                                  : target.getClass().getCreatureStats(target).getMagicEffects().get(ESM::MagicEffect::ResistBlightDisease).mMagnitude;
-
-                        int roll = std::rand()/ (static_cast<double> (RAND_MAX) + 1) * 100; // [0, 99]
-                        if (roll <= x)
-                        {
-                            // Fully resisted, show message
-                            if (target.getRefData().getHandle() == "player")
-                                MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicPCResisted}");
-                            magnitudeMult = 0;
-                        }
-                    }
-                    else
-                    {
-                        magnitudeMult = MWMechanics::getEffectMultiplier(effectIt->mEffectID, target, caster, spell);
-                        if (magnitudeMult == 0)
-                        {
-                            // Fully resisted, show message
-                            if (target.getRefData().getHandle() == "player")
-                                MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicPCResisted}");
-                            else
-                                MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicTargetResisted}");
-                        }
+                        // Fully resisted, show message
+                        if (target.getRefData().getHandle() == "player")
+                            MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicPCResisted}");
+                        else
+                            MWBase::Environment::get().getWindowManager()->messageBox("#{sMagicTargetResisted}");
                     }
                 }
             }

apps/openmw/mwmechanics/spellcasting.hpp

@@ -140,7 +140,7 @@ namespace MWMechanics
             float x = (willpower + 0.1 * luck) * stats.getFatigueTerm();
 
             // This makes spells that are easy to cast harder to resist and vice versa
-            if (spell != NULL)
+            if (spell != NULL && caster.getClass().isActor())
             {
                 float castChance = getSpellSuccessChance(spell, caster);
                 if (castChance > 0)