So, I was playing in the tower and when I fought the consuming horror on floor 16 with my pugilist, he was very strong and that's how I beat him:
He had 90% health, I stood near the lava and waited for him to come one block below me and he did that, then I used vital strike on him (Threw him over myself, so we switched positions) and then used uppercut on him and he fell in the lava. I also had to use magic mirror and summon a spirit.
I remember playing this back in 2013 on Armor Games. 2013 - best year for flash games. Best games of the year: Sinjid, Strike Force Heroes, Kingdom Rush Frontiers, this one and many others.