A Thrall 'boss' fight could be sweet. You get dropped into a hive chamber where wizards have been working on making more useful thralls. Heavily armored, extremely aggressivel. A piece of plate armor encases there head, hiding their usual weakpoint. They are blind, and seek you out by an ability to sense your light. They would have a weakpoint from behind, and in order to make use of it, you would have to, mask your precence with the darkness (a debuff that slows your skill recharge rate and blocks recovery)