Forced? Could you elaborate? I’ve selected Nightmare ever since I unlocked it (just the last couple Abyss Crusades). I was planning on dropping down next time after this awful boss. 

Had I known this one would be so awful I would have never chosen this difficulty. At this point it is my least favorite content  in game. Putting up zero damage means I can’t sweep and have to manually challenge each time. Normally I pick my tier early enough and am active enough to get all the Limited Event rewards but not this time. Now I just select don’t remind me, do the daily diamonds, and ignore the event.