fix(Scripts/HellfireRamparts): Nazan should descend when Vazruden rea… (#13876)

fix(Scripts/HellfireRamparts): Nazan should descend when Vazruden reaches 35%.

Fixes #13741

src/server/scripts/Outland/HellfireCitadel/HellfireRamparts/boss_vazruden_the_herald.cpp

@@ -273,6 +273,7 @@ public:
         void Reset() override
         {
             events.Reset();
+            _nazanCalled = false;
         }
 
         void EnterEvadeMode(EvadeReason /*why*/) override
@@ -296,9 +297,17 @@ public:
             }
         }
 
+        void DamageTaken(Unit* /*attacker*/, uint32& damage, DamageEffectType /*type*/, SpellSchoolMask /*school*/) override
+        {
+            if (!_nazanCalled && me->HealthBelowPctDamaged(35, damage))
+            {
+                _nazanCalled = true;
+                me->CastSpell(me, SPELL_CALL_NAZAN, true);
+            }
+        }
+
         void JustDied(Unit*) override
         {
-            me->CastSpell(me, SPELL_CALL_NAZAN, true);
             Talk(SAY_DIE);
         }
 
@@ -324,6 +333,7 @@ public:
 
     private:
         EventMap events;
+        bool _nazanCalled;
     };
 
     CreatureAI* GetAI(Creature* creature) const override