I found code for a third Dungeon Difficulty in the client i was woundering how i could enable it on trinitycore.
I found theses codes in the client
DUNGEON_DIFFICULTY3 = "Epic (Unused)";
UnitPopupButtons["DUNGEON_DIFFICULTY3"] = { text = DUNGEON_DIFFICULTY3, dist = 0 };
I managed to make it visable in-game but atm the button is a dud (I renamed it to Mythic)