Single Status Update
Here's a thought: A boss that has infinite transformations which are procedurally generated. Player has to pay attention to dialogue to figure out that there is a way to stop them from transforming for a time so that they can finish them off. Each time the boss gets low it says "This isn't even my final form!" What's even more fun is that eventually such a boss will spawn some challenges to see how many bosses one can get through before finally dying.