Core/Auras: reworked multiplicative AuraEffects calculation

- Splitted containers for flat modifiers and pct modifiers, as they now have different handling
- Amount is now multiplied only on apply; on unapply, iterate through auras and reset the counter
- Fixes many cases of rounding error due to applying/unapplying of small factors
- Allows amounts to be zeroed (ie with an AuraEffect of amount -100)
- Do a partial revert of 6dc37a9add631888fe5fbcd43d19c2b07bed8a57, auras should update amounts only for items allowed (ie no more giving crit to a sword while having an axe in the other hand and being Poleaxe spec'd)
- SPELL_AURA_MOD_SCALE now scales additively, rather than multiplicatively (checked in sniffs)

Closes #18687

1 files changed, 6 insertions, 12 deletions

diff --git a/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp b/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp
index 4616f960a5e..6ad3d2257b5 100644
--- a/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp
+++ b/src/server/scripts/Northrend/Naxxramas/boss_kelthuzad.cpp
@@ -875,26 +875,20 @@ public:
     {
         PrepareAuraScript(spell_kelthuzad_chains_AuraScript);
 
-        void HandleApply(AuraEffect const* /*eff*/, AuraEffectHandleModes /*mode*/)
+        void HandleApply(AuraEffect const* aurEff, AuraEffectHandleModes mode)
         {
-            Unit* target = GetTarget();
-            float scale = target->GetObjectScale();
-            ApplyPercentModFloatVar(scale, 200.0f, true);
-            target->SetObjectScale(scale);
+            aurEff->HandleAuraModScale(GetTargetApplication(), mode, true);
         }
 
-        void HandleRemove(AuraEffect const* /*eff*/, AuraEffectHandleModes /*mode*/)
+        void HandleRemove(AuraEffect const* aurEff, AuraEffectHandleModes mode)
         {
-            Unit* target = GetTarget();
-            float scale = target->GetObjectScale();
-            ApplyPercentModFloatVar(scale, 200.0f, false);
-            target->SetObjectScale(scale);
+            aurEff->HandleAuraModScale(GetTargetApplication(), mode, false);
         }
 
         void Register() override
         {
-            AfterEffectApply += AuraEffectApplyFn(spell_kelthuzad_chains_AuraScript::HandleApply, EFFECT_0, SPELL_AURA_AOE_CHARM, AURA_EFFECT_HANDLE_REAL);
-            AfterEffectRemove += AuraEffectApplyFn(spell_kelthuzad_chains_AuraScript::HandleRemove, EFFECT_0, SPELL_AURA_AOE_CHARM, AURA_EFFECT_HANDLE_REAL);
+            AfterEffectApply += AuraEffectApplyFn(spell_kelthuzad_chains_AuraScript::HandleApply, EFFECT_1, SPELL_AURA_MOD_DAMAGE_PERCENT_DONE, AURA_EFFECT_HANDLE_REAL);
+            AfterEffectRemove += AuraEffectApplyFn(spell_kelthuzad_chains_AuraScript::HandleRemove, EFFECT_1, SPELL_AURA_MOD_DAMAGE_PERCENT_DONE, AURA_EFFECT_HANDLE_REAL);
         }
     };