UnderMine

This is an optional boss fight that will appear randomly in Delvemore on any floor. The best tactic I found was to throw your axe at one gargoyle at a time while jumping around the room. Their attacks only go in a straight line forward, so as long as you stay far enough away and jump repeatedly, you should be able to avoid being hit often. The gargoyles will sure back to stone at least once each where they heal and become invulnerable. Take that time to focus on another one and as they are whittled down, you'll start to be able to attack them up close from the side or back while they're in the middle of their attacks, immobile and vulnerable.