Nice game idea. The companion is really nice way of implementing the theme. Also I like the graphics very much. The characters and env-art is really good. But compared to that the floor is boring.
I like the system how you've implemented the skills. Turning it into a minigame while slowing down the enemies is really a nice mechanic and allows playing around with different tactics. One thing which you could improve here would be to have a auto-fire on basic-attack while the mouse button is pressed.
Overall the game could explain more the player. So it took some time to figure out that my companion is also the shop. Then in the shop it would be good to see which spell is selected + the costs. I first wanted to have some description of the spells but I also enjoyed finding out what certain spells will do. So I think it is ok to let the player explore the spells instead of presenting everything.
The game kept me in for some rounds. So good work :-)