fix(Karazhan/Nightbane): no longer killable during flight (azerothcor…

…e#18890)

add unkillable during flight phase

_flying: takeoff/landing, moving to location
Phase 2: in the air and casting air spells

src/server/scripts/EasternKingdoms/Karazhan/boss_nightbane.cpp

@@ -109,6 +109,18 @@ struct boss_nightbane : public BossAI
         me->GetMotionMaster()->MoveTakeoff(POINT_DESPAWN, -11013.246f, -1770.5212f, 166.50139f);
     }
 
+    void DamageTaken(Unit* attacker, uint32& damage, DamageEffectType damageEffectType, SpellSchoolMask spellSchoolMask) override
+    {
+        if (_flying || Phase == 2)
+        {
+            if (damage >= me->GetHealth())
+            {
+                damage = me->GetHealth() - 1;
+            }
+        }
+        BossAI::DamageTaken(attacker, damage, damageEffectType, spellSchoolMask);
+    }
+
     void JustEngagedWith(Unit* who) override
     {
         BossAI::JustEngagedWith(who);