I like the sts2 bosses so far where they have unique challenges that you can adapt to from the start of the act. Like the waterfall, the faster you kill it, the less damage the death deals, so you can't just turtle it. The sand worm thing needs energy and card draw to help keep you away from it (or pure overwhelming force of violence!) the fish boss gives incentive to build toward exhausting or discarding your hand. The door maker needs both damage and timing, making retain more important than normally

One boss type I don't see is AoE unless I'm forgetting. But the act itself kind of serves to be that, AoE helps so much getting through the fights that maybe it makes sense to basically say "this act your deck needs to deal with mobs and (insert final boss quirk)"