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 74af880217)

src/server/scripts/World/item_scripts.cpp

@@ -250,7 +250,7 @@ public:
         {
             summon->SetVisible(false);
             summon->SetReactState(REACT_PASSIVE);
-            summon->AddUnitFlag(UNIT_FLAG_IMMUNE_TO_PC);
+            summon->SetImmuneToPC(true);
         }
         return false;
     }