fix(Core/Spells): Master of Elements mana refund with Living Bomb and base cost calculation (#24775)

Co-authored-by: blinkysc <blinkysc@users.noreply.github.com>

src/server/scripts/Spells/spell_mage.cpp

@@ -70,7 +70,8 @@ enum MageSpells
     SPELL_MAGE_CHILLED_R2                        = 12485,
     SPELL_MAGE_CHILLED_R3                        = 12486,
     SPELL_MAGE_MANA_SURGE                        = 37445,
-    SPELL_MAGE_FROST_NOVA                        = 122
+    SPELL_MAGE_FROST_NOVA                        = 122,
+    SPELL_MAGE_LIVING_BOMB_R1                    = 44457
 };
 
 enum MageSpellIcons
@@ -807,7 +808,7 @@ class spell_mage_master_of_elements : public AuraScript
 
     bool Validate(SpellInfo const* /*spellInfo*/) override
     {
-        return ValidateSpellInfo({ SPELL_MAGE_MASTER_OF_ELEMENTS_ENERGIZE });
+        return ValidateSpellInfo({ SPELL_MAGE_MASTER_OF_ELEMENTS_ENERGIZE, SPELL_MAGE_LIVING_BOMB_R1 });
     }
 
     bool CheckProc(ProcEventInfo& eventInfo)
@@ -823,7 +824,23 @@ class spell_mage_master_of_elements : public AuraScript
     {
         PreventDefaultAction();
 
-        int32 mana = eventInfo.GetDamageInfo()->GetSpellInfo()->CalcPowerCost(GetTarget(), eventInfo.GetDamageInfo()->GetSchoolMask());
+        SpellInfo const* spellInfo = eventInfo.GetDamageInfo()->GetSpellInfo();
+
+        // Living Bomb explosion has no mana cost, use the aura spell's cost instead
+        if (spellInfo->SpellFamilyName == SPELLFAMILY_MAGE
+            && spellInfo->SpellIconID == MAGE_ICON_LIVING_BOMB
+            && !spellInfo->ManaCost && !spellInfo->ManaCostPercentage)
+        {
+            uint8 rank = sSpellMgr->GetSpellRank(spellInfo->Id);
+            spellInfo = sSpellMgr->GetSpellInfo(
+                sSpellMgr->GetSpellWithRank(SPELL_MAGE_LIVING_BOMB_R1, rank));
+            if (!spellInfo)
+                return;
+        }
+
+        // Use base mana cost (ManaCost + ManaCostPercentage) without spell mods,
+        // as the talent refunds based on "base mana cost"
+        int32 mana = spellInfo->ManaCost + int32(CalculatePct(GetTarget()->GetCreateMana(), spellInfo->ManaCostPercentage));
         mana = CalculatePct(mana, aurEff->GetAmount());
 
         if (mana > 0)