Cave Trolls are the toughest creature in the game. Having lots of health, they are tough to kill, as well dealing a lot of damage. Something special about them, is that they can do many things a Blockhead can; Walk, climb,place torches... They always spawn very close to a treasure, and guard it. If a Blockhead aproaches, they will chase the blockhead. If the blockhead goes away, they will simply go back to their chest. Still,they are slow, giving a rested Blockhead a chance to flee. They spawn deep underground, so you don't have to worry about them in the surface.
A Cave Troll,guarding a Golden Chest