Wow.

So (spoilers) the PoE level 34 boss can regenerate health. We weren't sure why or how to stop him, so we just burned him. And guess what? We killed him before his health could regen. Apparently there's a group of enemies you have to kill quickly to prevent his health from regenerating each time they spawn. Cool right? Not when you don;t even have to deal with it.

You unknowingly killed him the way the designers wanted you to -- fast. Bad design that the super dregs spawn so infrequently and in such large numbers in repeated locations. Would have been better if he had more health and there were fewer, more powerful super dregs. As it is, you have to just burn him between or before heals and ignore the super dregs.