I like it; played all evening. The main problem I had was not being able to tell how much damage the enemy would inflict or how much damage skulls would do to the enemy.
Giving XP only for damage directly inflicted seems mistaken; forcing the enemy to take a skull is clever and should get points -- probably even bonus. Similarly there should maybe be points for nabbing the potion, and maybe bonus (or minus?) based on number of turns taken? As it stands there's no reward for playing well, only for killing the enemy.
Balance seems fine for this (since you're always going to die and that's all there is); additional content and play modes would probably change that.
More kinds of actions would be interesting; that might call for a bigger grid, which would also be interesting. Both ideas might mess up the action-balance though -- hard to guess.
Nicely made! I really like this mechanic.