fix(Scripts/Ulduar): make Mimiron's Aerial Command Unit chase players (#26625)

Co-authored-by: Unholychick <lucas__jensen@hotmail.com>
Co-authored-by: Chaouki Dhib <chaodhib@gmail.com>
Co-authored-by: sirikfoll <sirikfoll@hotmail.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

data/sql/updates/pending_db_world/rev_1784088692116509100.sql

@@ -0,0 +1,7 @@
+-- Aerial Command Unit: hover height and flags to match TDB (hover-based chase)
+-- 256 = UNIT_FLAG_IMMUNE_TO_PC (cleared by script at phase start), 512 = CREATURE_FLAG_EXTRA_NO_MOVE_FLAGS_UPDATE
+UPDATE `creature_template` SET `HoverHeight` = 15, `unit_flags` = `unit_flags`|256, `flags_extra` = `flags_extra`|512 WHERE `entry` IN (33670, 34109);
+
+-- Values ported from TrinityCore (TrinityCore/TrinityCore@7c13b383); zeroed combat reach
+-- made the hovering ACU unreachable for Magnetic Core's 15y check
+UPDATE `creature_model_info` SET `BoundingRadius` = 0.31, `CombatReach` = 5 WHERE `DisplayID` = 28979;

src/server/scripts/Northrend/Ulduar/Ulduar/boss_mimiron.cpp

@@ -264,7 +264,8 @@ enum Texts
 #define GetVX001() instance->GetCreature(DATA_MIMIRON_VX001)
 #define GetACU() instance->GetCreature(DATA_MIMIRON_ACU)
 
-Position const ACUSummonPos = { 2742.6265f, 2568.0571f, 377.22076f, 0.0f }; /// @todo: replace with sniffed position
+// Z is above hover height (15y) so that activating hover does not relocate the ACU upwards
+Position const ACUSummonPos = { 2744.650f, 2569.460f, 380.0f, 3.141593f };
 
 struct boss_mimiron : public BossAI
 {
@@ -1513,7 +1514,8 @@ struct npc_ulduar_aerial_command_unit : public ScriptedAI
         _isDefeated = false;
         _events.Reset();
         _summons.DespawnAll();
-        me->SetCombatMovement(false); /// @todo: research ACU behaviour
+        me->SetHover(false);
+        me->SetDisableGravity(true);
     }
 
     void SetData(uint32 id, uint32 value) override
@@ -1528,7 +1530,12 @@ struct npc_ulduar_aerial_command_unit : public ScriptedAI
                     break;
                 case 3:
                     _phase = 3;
+                    // Hover instead of disabled gravity: chase then keeps the ACU at
+                    // HoverHeight above ground instead of dragging it to ground level.
+                    me->SetDisableGravity(false);
+                    me->SetHover(true);
                     me->RemoveUnitFlag(UNIT_FLAG_NOT_SELECTABLE);
+                    me->SetImmuneToPC(false);
                     DoZoneInCombat();
                     _events.Reset();
                     _events.ScheduleEvent(EVENT_SUMMON_BOMB_BOT, 15s);
@@ -1560,14 +1567,24 @@ struct npc_ulduar_aerial_command_unit : public ScriptedAI
                 me->CastStop();
                 me->AttackStop();
                 me->SetReactState(REACT_PASSIVE);
-                me->SetDisableGravity(false);
+                // Raw flag removal first: MoveFall lands at ground + hover height, which would
+                // keep the ACU airborne, and SetHover(false) would relocate it without a spline.
+                // SetHover(false) afterwards is relocation-free and tells the client to stop
+                // hovering, else it keeps floating the grounded unit back up
+                me->RemoveUnitMovementFlag(MOVEMENTFLAG_HOVER);
                 me->GetMotionMaster()->MoveFall();
+                me->SetHover(false);
                 _events.DelayEvents(25s);
                 break;
             case DO_ENABLE_AERIAL:
+                if (_isDefeated)
+                    break;
                 me->SetDisableGravity(true);
-                me->GetMotionMaster()->MovePoint(0, me->GetPositionX(), me->GetPositionY(), me->GetPositionZ() + 10.0f);
+                // 16y: above hover height (15y) so SetHover does not relocate it further up
+                me->GetMotionMaster()->MovePoint(0, me->GetPositionX(), me->GetPositionY(), me->GetPositionZ() + 16.0f);
                 me->m_Events.AddEventAtOffset([&] {
+                    me->SetDisableGravity(false);
+                    me->SetHover(true);
                     me->SetReactState(REACT_AGGRESSIVE);
                 }, 2s);
                 break;
@@ -1599,6 +1616,7 @@ struct npc_ulduar_aerial_command_unit : public ScriptedAI
                     me->InterruptNonMeleeSpells(false);
                     me->RemoveAllAurasExceptType(SPELL_AURA_CONTROL_VEHICLE);
 
+                    me->SetDisableGravity(true);
                     me->GetMotionMaster()->MovePoint(0, 2744.65f, 2569.46f, 381.34f);
 
                     if (Creature* c = GetMimiron())