I'm stuck on the same level: the game is long enough that feeling like you can soft-lock yourself through upgrade choices or by skipping too many of the optional challenge areas is a bit frustrating. I feel like I probably could replay the game and end up with a stronger Kevin for this level, but I might just stop playing entirely instead. Because the puzzles are so stringent with how they want to be solved, it seems like set spell upgrades might create a more even experience.
Overall though, this game is extremely charming! Drawing the spells is cool, there's a ton of personality to the game and I had fun with it.