diff --git a/apps/openmw/engine.cpp b/apps/openmw/engine.cpp
index 00ad90a02..2eebb8c28 100644
--- a/apps/openmw/engine.cpp
+++ b/apps/openmw/engine.cpp
@@ -478,7 +478,7 @@ void OMW::Engine::go()
     }
 
     // Start the main rendering loop
-    while (!mEnvironment.get().getStateManager()->hasQuitRequest())
+    while (!MWBase::Environment::get().getStateManager()->hasQuitRequest())
         Ogre::Root::getSingleton().renderOneFrame();
 
     // Save user settings
diff --git a/apps/openmw/mwclass/repair.hpp b/apps/openmw/mwclass/repair.hpp
index 17730d6ec..f89258234 100644
--- a/apps/openmw/mwclass/repair.hpp
+++ b/apps/openmw/mwclass/repair.hpp
@@ -63,7 +63,7 @@ namespace MWClass
 
             virtual int getItemMaxHealth (const MWWorld::Ptr& ptr) const;
             ///< Return item max health or throw an exception, if class does not have item health
-            /// (default implementation: throw an exceoption)
+            /// (default implementation: throw an exception)
 
             virtual float getWeight (const MWWorld::Ptr& ptr) const;
 
diff --git a/apps/openmw/mwmechanics/spellcasting.cpp b/apps/openmw/mwmechanics/spellcasting.cpp
index fab512a0d..35432e979 100644
--- a/apps/openmw/mwmechanics/spellcasting.cpp
+++ b/apps/openmw/mwmechanics/spellcasting.cpp
@@ -246,10 +246,7 @@ namespace MWMechanics
                               const ESM::Spell* spell, const MagicEffects* effects)
     {
         float resistance = getEffectResistance(effectId, actor, caster, spell, effects);
-        if (resistance >= 0)
-            return 1 - resistance / 100.f;
-        else
-            return -(resistance-100) / 100.f;
+        return 1 - resistance / 100.f;
     }
 
     /// Check if the given affect can be applied to the target. If \a castByPlayer, emits a message box on failure.
diff --git a/apps/openmw/mwmechanics/spellcasting.hpp b/apps/openmw/mwmechanics/spellcasting.hpp
index 66e91d055..c01fede37 100644
--- a/apps/openmw/mwmechanics/spellcasting.hpp
+++ b/apps/openmw/mwmechanics/spellcasting.hpp
@@ -51,6 +51,10 @@ namespace MWMechanics
     float getEffectResistance (short effectId, const MWWorld::Ptr& actor, const MWWorld::Ptr& caster,
                                const ESM::Spell* spell = NULL, const MagicEffects* effects = NULL);
 
+    /// Get an effect multiplier for applying an effect cast by the given actor in the given spell (optional).
+    /// @return effect multiplier from 0 to 2.  (100% net resistance to 100% net weakness)
+    /// @param effects Override the actor's current magicEffects. Useful if there are effects currently
+    ///                being applied (but not applied yet) that should also be considered.
     float getEffectMultiplier(short effectId, const MWWorld::Ptr& actor, const MWWorld::Ptr& caster,
                               const ESM::Spell* spell = NULL, const MagicEffects* effects = NULL);
 
diff --git a/apps/openmw/mwworld/class.hpp b/apps/openmw/mwworld/class.hpp
index 33b5f1e66..5f266b45c 100644
--- a/apps/openmw/mwworld/class.hpp
+++ b/apps/openmw/mwworld/class.hpp
@@ -96,7 +96,7 @@ namespace MWWorld
 
             virtual MWMechanics::CreatureStats& getCreatureStats (const Ptr& ptr) const;
             ///< Return creature stats or throw an exception, if class does not have creature stats
-            /// (default implementation: throw an exceoption)
+            /// (default implementation: throw an exception)
 
             virtual bool hasToolTip (const Ptr& ptr) const;
             ///< @return true if this object has a tooltip when focused (default implementation: false)
@@ -106,7 +106,7 @@ namespace MWWorld
 
             virtual MWMechanics::NpcStats& getNpcStats (const Ptr& ptr) const;
             ///< Return NPC stats or throw an exception, if class does not have NPC stats
-            /// (default implementation: throw an exceoption)
+            /// (default implementation: throw an exception)
 
             virtual bool hasItemHealth (const Ptr& ptr) const;
             ///< \return Item health data available? (default implementation: false)
@@ -123,7 +123,7 @@ namespace MWWorld
             /// of the given attacker, and whoever is hit.
             /// \param type - type of attack, one of the MWMechanics::CreatureStats::AttackType
             ///               enums. ignored for creature attacks.
-            /// (default implementation: throw an exceoption)
+            /// (default implementation: throw an exception)
 
             virtual void onHit(const MWWorld::Ptr &ptr, float damage, bool ishealth, const MWWorld::Ptr &object, const MWWorld::Ptr &attacker, bool successful) const;
             ///< Alerts \a ptr that it's being hit for \a damage points to health if \a ishealth is
@@ -139,7 +139,7 @@ namespace MWWorld
             ///< Sets a new current health value for the actor, optionally specifying the object causing
             /// the change. Use this instead of using CreatureStats directly as this will make sure the
             /// correct dialog and actor states are properly handled when being hurt or healed.
-            /// (default implementation: throw an exceoption)
+            /// (default implementation: throw an exception)
 
             virtual boost::shared_ptr<Action> activate (const Ptr& ptr, const Ptr& actor) const;
             ///< Generate action for activation (default implementation: return a null action).
@@ -151,11 +151,11 @@ namespace MWWorld
 
             virtual ContainerStore& getContainerStore (const Ptr& ptr) const;
             ///< Return container store or throw an exception, if class does not have a
-            /// container store (default implementation: throw an exceoption)
+            /// container store (default implementation: throw an exception)
 
             virtual InventoryStore& getInventoryStore (const Ptr& ptr) const;
             ///< Return inventory store or throw an exception, if class does not have a
-            /// inventory store (default implementation: throw an exceoption)
+            /// inventory store (default implementation: throw an exception)
 
             virtual bool hasInventoryStore (const Ptr& ptr) const;
             ///< Does this object have an inventory store, i.e. equipment slots? (default implementation: false)