Thank you so much for the thorough feedback, and you make a lot of great points. The "too difficult at the beginning" problem is one I've been wrestling with and gradually adjusting, and I've been torn whether to allow a fifth character. I've gradually been leaning toward yes, even though that will require a lot of code changes (not too many, though).
The targets 1-4 question is asking which group of monsters to cast at, which only makes sense when there's more than one group of monsters. I plan to make those buttons show the monster group names instead of numbers in a future version.
There's much to think about and much to adjust, and I really appreciate you taking the time to test out the game and share your thoughts. :)