Fix immunity system for many spells.

src/server/game/Entities/Creature/Creature.cpp

@@ -1643,7 +1643,20 @@ bool Creature::IsImmunedToSpell(SpellInfo const* spellInfo)
     if (!spellInfo)
         return false;
 
-    if (GetCreatureInfo()->MechanicImmuneMask & (1 << (spellInfo->Mechanic - 1)))
+    // Spells that don't have effectMechanics.
+    if (!spellInfo->HasAnyEffectMechanic() && GetCreatureInfo()->MechanicImmuneMask & (1 << (spellInfo->Mechanic - 1)))
+        return true;
+
+    // This check must be done instead of 'if (GetCreatureInfo()->MechanicImmuneMask & (1 << (spellInfo->Mechanic - 1)))' for not break
+    // the check of mechanic immunity on DB (tested) because GetCreatureInfo()->MechanicImmuneMask and m_spellImmune[IMMUNITY_MECHANIC] don't have same data.
+    bool immunedToAllEffects = true;
+    for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
+        if (!IsImmunedToSpellEffect(spellInfo, i))
+        {
+            immunedToAllEffects = false;
+            break;
+        }
+    if (immunedToAllEffects)
         return true;
 
     return Unit::IsImmunedToSpell(spellInfo);

src/server/game/Entities/Unit/Unit.cpp

@@ -11448,7 +11448,8 @@ bool Unit::IsImmunedToSpell(SpellInfo const* spellInfo)
                 return true;
     }
 
-    if (spellInfo->Mechanic)
+    // Spells that don't have effectMechanics.
+    if (!spellInfo->HasAnyEffectMechanic() && spellInfo->Mechanic)
     {
         SpellImmuneList const& mechanicList = m_spellImmune[IMMUNITY_MECHANIC];
         for (SpellImmuneList::const_iterator itr = mechanicList.begin(); itr != mechanicList.end(); ++itr)
@@ -11456,14 +11457,19 @@ bool Unit::IsImmunedToSpell(SpellInfo const* spellInfo)
                 return true;
     }
 
-    for (int i = 0; i < MAX_SPELL_EFFECTS; ++i)
+    bool immuneToAllEffects = true;
+    for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
     {
         // State/effect immunities applied by aura expect full spell immunity
         // Ignore effects with mechanic, they are supposed to be checked separately
-        if (!spellInfo->Effects[i].Mechanic)
+        if (spellInfo->Effects[i].Mechanic || !IsImmunedToSpellEffect(spellInfo, i))
-            if (IsImmunedToSpellEffect(spellInfo, i))
+        {
-                return true;
+            immuneToAllEffects = false;
+            break;
         }
+    }
+    if (immuneToAllEffects) //Return immune only if the target is immune to all spell effects.
+        return true;
 
     if (spellInfo->Id != 42292 && spellInfo->Id !=59752)
     {

src/server/game/Spells/Spell.cpp

@@ -1562,7 +1562,7 @@ SpellMissInfo Spell::DoSpellHitOnUnit(Unit* unit, const uint32 effectMask, bool
     }
 
     for (uint32 effectNumber = 0; effectNumber < MAX_SPELL_EFFECTS; ++effectNumber)
-        if (effectMask & (1 << effectNumber))
+        if (effectMask & (1 << effectNumber) && !unit->IsImmunedToSpellEffect(m_spellInfo, effectNumber)) //Handle effect only if the target isn't immune.
             HandleEffects(unit, NULL, NULL, effectNumber, SPELL_EFFECT_HANDLE_HIT_TARGET);
 
     return SPELL_MISS_NONE;

src/server/game/Spells/SpellInfo.cpp

@@ -1755,6 +1755,14 @@ Mechanics SpellInfo::GetEffectMechanic(uint8 effIndex) const
     return MECHANIC_NONE;
 }
 
+bool SpellInfo::HasAnyEffectMechanic() const
+{
+    for (uint8 i = 0; i < MAX_SPELL_EFFECTS; ++i)
+        if (Effects[i].Mechanic)
+            return true;
+    return false;
+}
+
 uint32 SpellInfo::GetDispelMask() const
 {
     return GetDispelMask(DispelType(Dispel));

src/server/game/Spells/SpellInfo.h

@@ -446,6 +446,7 @@ public:
     uint32 GetEffectMechanicMask(uint8 effIndex) const;
     uint32 GetSpellMechanicMaskByEffectMask(uint32 effectMask) const;
     Mechanics GetEffectMechanic(uint8 effIndex) const;
+    bool HasAnyEffectMechanic() const;
     uint32 GetDispelMask() const;
     static uint32 GetDispelMask(DispelType type);
     uint32 GetExplicitTargetMask() const;