Loved unlocking new words to make new spells with. Your system here is intuitive and fun to see the results of. I can see that main room being the "test room" for a future release (although I wouldn't want to walk all the way there after updating my spells)
I put everything into Wisdom, and at some point my spells got slower, but I attributed this to some spell effects changing the cooldown (I wouldn't know, I can't read!).
The boss really escalated the challenge, so I'd love to see more spells added to combat them. Awesome!