Maze with fragments of the swor of Crota, Shrieker sub boss (haven't been used much never as a boss and they already have boss fight mechanics like closing up then firing seeking void things), Crota shielded In the darkness stuff that wizards use. (Kill special wizards who summoned him then use sword to temporarily take darkness shield down for everyone to shoot. Water deep enough to slow your movement and have thralls popping up from below.