Interesting game, Liking the shape shifting concept. I have a few issues though:
Moving up and down uses energy just as shape shifting. If you are out of energy, you can't do a thing. Feels like too much penalty. Hard to recover from it.
It's not bad that you transform into the enemy types and you can beat them as them, but maybe a rock-paper-scissors method would work better. Knight beats slime, wizard beats knight, Slime beats... wizard?