A fair start. The basic mechanics work well, but at the moment there is no skill or strategy here thanks to the limited use of heal and magic. Essentially every battle you use your three attempts with each, and then it boils down to whether you are lucky enough to hit and how lucky you are with the number generation.
More attack options would make for a more compeling game, with variation in how much damage they do balanced by how often they hit. Equally being able to regenerate magic attacks or heals would make using them more strategic. A guard or defensive option would also be useful to try and counter incoming magic attacks.
As it is the only reason to replay is the medals. It would be great to play because the game is fun and rewarding as your skill defeats your opponent, not luck.