This game has a very cool idea, but I think due to the controls, as well as the lack of feedback hold it back. The concept of using 1, 2, 3, and 4 to use attacks is not new, but a lot of games that use them often have the player move with the mouse. In this game I think adding the ability to use the special abilities by clicking on them as an additional option would add a lot.
Going more deeply with the attacks, I thought they were a little hard to use as I could not tell very easily if they had landed without looking at enemies health to double check. I think adding some visual like a particle effect as well as adding a sound effect when attacks land would help this a lot.
Attacks can also be interrupted by other attacks. I found that the most efficient way to attack enemies was to walk up to them, and then press 1, 2, 3, and 4 all at the same time, which would usually kill enemies in one shot. Being able to do this I'm assuming was not by design, and would recommend looking into a way around this. I think locking the enemies and player in place when attacking them would benefit the combat as well.