Hi, I'm Treeston, and welcome to Combat PR Prep Refactors.

Today, we're moving UNIT_FLAG_IMMUNE_TO_PC and UNIT_FLAG_IMMUNE_TO_NPC to higher-level abstraction so combat manager can react to it.
New methods on Unit:
- void SetImmuneTo<All/PC/NPC>(apply, keepCombat = false);
- bool IsImmuneTo<All/PC/NPC>() const;

(cherry picked from commit 74af880217fc567c9949d7557408718af889402f)

src/server/scripts/Spells/spell_quest.cpp

@@ -277,13 +277,13 @@ class spell_q11396_11399_force_shield_arcane_purple_x3 : public SpellScriptLoade
             void HandleEffectApply(AuraEffect const* /*aurEff*/, AuraEffectHandleModes /*mode*/)
             {
                 Unit* target = GetTarget();
-                target->AddUnitFlag(UNIT_FLAG_IMMUNE_TO_PC);
+                target->SetImmuneToPC(true);
                 target->AddUnitState(UNIT_STATE_ROOT);
             }
 
             void HandleEffectRemove(AuraEffect const* /*aurEff*/, AuraEffectHandleModes /*mode*/)
             {
-                GetTarget()->RemoveUnitFlag(UNIT_FLAG_IMMUNE_TO_PC);
+                GetTarget()->SetImmuneToPC(false);
             }
 
             void Register() override