Core/Auras: Do not remove auras unaffected by invincibility

* Mark WSG's Focused Assault and Brutal Assault as unaffected by immunities

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

@@ -7371,6 +7371,7 @@ bool Unit::IsImmunedToSpell(SpellInfo const* spellInfo, WorldObject const* caste
                 continue;
 
             SpellInfo const* immuneSpellInfo = sSpellMgr->GetSpellInfo(itr->second);
+
             // Consider the school immune if any of these conditions are not satisfied.
             // In case of no immuneSpellInfo, ignore that condition and check only the other conditions
             if ((immuneSpellInfo && !immuneSpellInfo->IsPositive()) || !spellInfo->IsPositive() || !caster || !IsFriendlyTo(caster))

src/server/game/Spells/SpellInfo.cpp

@@ -3150,7 +3150,11 @@ void SpellInfo::ApplyAllSpellImmunitiesTo(Unit* target, uint8 effIndex, bool app
     {
         target->ApplySpellImmune(Id, IMMUNITY_STATE, auraType, apply);
         if (apply && HasAttribute(SPELL_ATTR1_IMMUNITY_PURGES_EFFECT))
-            target->RemoveAurasByType(auraType);
+            target->RemoveAurasByType(auraType, [](AuraApplication const* aurApp) -> bool
+            {
+                // if the aura has SPELL_ATTR0_NO_IMMUNITIES, then it cannot be removed by immunity
+                return !aurApp->GetBase()->GetSpellInfo()->HasAttribute(SPELL_ATTR0_NO_IMMUNITIES);
+            });
     }
 
     for (SpellEffects effectType : immuneInfo->SpellEffectImmune)