A good length for a game jam! I enjoyed bouncing around and wondering what the next change would, and there was a great variety of different things that could happen. After killing all the monsters in the final enormous room, the game just stopped. I'm not sure if this was a bug or if that's just the end of the content. I couldn't move anywhere, or do anything, so I just alt-tabbed out to exit the game.

- Definitely if you were to add any graphics whatsoever, the first place I would do it is making the monsters react when damaged. If the main mechanic of the game is killing stuff, just make it feel satisfying, y'know?
- What was the difference between the two kinds of spells? I didn't notice any strategic advantage to one over the other, so I just spammed them randomly and got through the game just fine.
- The wizard never took any damage. Not sure if that was intended, but once I realized I had nothing to be afraid of, that meant the only challenge there was was platforming (and I was actually pretty bad at the platforming on the bottom right part of the map, where I kept hitting my head on the ceiling and then falling between the platforms. Got there in the end, but it wasn't fun to deal with the physics, and I doubt that was intended to be as much of a challenge as it was for me.

I think that taking no damage, what the previous commenter has noticed, is a bug with the shield -- once I've used the spell, I was able to take damage and die >,< (I think so -- the game froze).
You had a good idea with incorporating the theme!