fix(Scripts/Spells): Deep Freeze Immunity State proc (#26168)

Co-authored-by: Ovahlord <dreadkiller@gmx.de>

data/sql/updates/pending_db_world/rev_1781291919238142004.sql

@@ -0,0 +1,4 @@
+--
+-- Fix Deep Freeze: only proc trigger spell 71757 on permanently stun-immune creatures
+DELETE FROM `spell_script_names` WHERE `spell_id`=71761;
+INSERT INTO `spell_script_names` (`spell_id`, `ScriptName`) VALUES (71761, 'spell_mage_deep_freeze_immunity_state');

src/server/scripts/Spells/spell_mage.cpp

@@ -1588,6 +1588,25 @@ class spell_mage_missile_barrage_proc : public AuraScript
     }
 };
 
+// 71761 - Deep Freeze Immunity State
+class spell_mage_deep_freeze_immunity_state : public AuraScript
+{
+    PrepareAuraScript(spell_mage_deep_freeze_immunity_state);
+
+    bool CheckEffectProc(AuraEffect const* /*aurEff*/, ProcEventInfo& eventInfo)
+    {
+        if (!eventInfo.GetProcTarget() || !eventInfo.GetProcTarget()->IsCreature())
+            return false;
+
+        return eventInfo.GetProcTarget()->ToCreature()->HasMechanicTemplateImmunity(1ULL << MECHANIC_STUN);
+    }
+
+    void Register() override
+    {
+        DoCheckEffectProc += AuraCheckEffectProcFn(spell_mage_deep_freeze_immunity_state::CheckEffectProc, EFFECT_0, SPELL_AURA_PROC_TRIGGER_SPELL);
+    }
+};
+
 void AddSC_mage_spell_scripts()
 {
     RegisterSpellScript(spell_mage_arcane_blast);
@@ -1632,4 +1651,5 @@ void AddSC_mage_spell_scripts()
     RegisterSpellScript(spell_mage_summon_water_elemental);
     RegisterSpellScript(spell_mage_fingers_of_frost);
     RegisterSpellScript(spell_mage_magic_absorption);
+    RegisterSpellScript(spell_mage_deep_freeze_immunity_state);
 }