It is interesting, but VERY RISKY.
I didn't mean take out the Hellbois, I just meant don't add a third if they make it bigger. A trinket sounds nice. What if they made the Hellboi a mini-boss who dropped a trinket. Make him level 5, and make him the first square of the maze. You have to hit him once to move him, and then he'll lifesteal again. Give him level 5 damage, but 1 hp.