What a fun game !! I spent quite some time trying out all the different spell levels :D
They all feel very different and the fact that the enemies also attack you with spells makes for a lot of unique situations.
I would have loved that the damage you do versus enemy of a weak type was way stronger (almost one shot kill). Because at the moment it feels way easier to play with a simple spell. Playing with all 4 spells is the most difficult playstyle, but with enough skills it should be the most efficient way to play :)
Cheers and congrats on the game, my favorite so far !