I think the big issue is moving the player, the only way to do that is with the magnet (as far as I know) and the magnet deals damage to you unless you use another magnet, and I feel like the magnet is too quick. I think that idea is interested having to switch back and forth consistently to avoid damage and deal it to the boss at the same time, so I think difficulty balancing would do well. Also prevent the boss from attack during the tutorial. Other than that, cool concept, cool combat.