fix(core/scripting) Calculate percent-based damage before `ModifyPeri…

…odicDamageAurasTick` hook (#17387)

Moved damage calculation for `SPELL_AURA_PERIODIC_DAMAGE_PERCENT` to before the hook.

Co-authored-by: KJack <kjack@electricnightowl.com>

src/server/game/Spells/Auras/SpellAuraEffects.cpp

@@ -6298,6 +6298,13 @@ void AuraEffect::HandlePeriodicDamageAurasTick(Unit* target, Unit* caster) const
     // ignore non positive values (can be result apply spellmods to aura damage
     uint32 damage = std::max(GetAmount(), 0);
 
+    // If the damage is percent-max-health based, calculate damage before the Modify hook
+    if (GetAuraType() == SPELL_AURA_PERIODIC_DAMAGE_PERCENT)
+    {
+        // xinef: ceil obtained value, it may happen that 10 ticks for 10% damage may not kill owner
+        damage = uint32(std::ceil(CalculatePct<float, float>(target->GetMaxHealth(), damage)));
+    }
+
     // Script Hook For HandlePeriodicDamageAurasTick -- Allow scripts to change the Damage pre class mitigation calculations
     sScriptMgr->ModifyPeriodicDamageAurasTick(target, caster, damage, GetSpellInfo());
 
@@ -6329,8 +6336,6 @@ void AuraEffect::HandlePeriodicDamageAurasTick(Unit* target, Unit* caster) const
             // 5..8 ticks have normal tick damage
         }
     }
-    else // xinef: ceil obtained value, it may happen that 10 ticks for 10% damage may not kill owner
-        damage = uint32(std::ceil(CalculatePct<float, float>(target->GetMaxHealth(), damage)));
 
     // calculate crit chance
     bool crit = false;