Really well made and great style. As others have pointed out, everything feels really cohesive with all the UI elements moving the beat and such. Fun theme and great artwork, maybe the music could have been a bit more present and with some more time it'd be nice to have more musical sound effects for the spell cassettes.
I really love the core idea as well, having to balance how many power ups vs. how many offesive abilities, picking which things go first so you can sequence fire into disco balls or make sure that your most powerful spell sticks on screen for long enough etc. It's really smart, well done!