I've got two more enemies I'd started work on that didn't make it in, with a total of three more possible I'd drafted ideas for. Just ran out of time; the other enemies would have fixed the problem as well, they were both focused on forcing the player away from the tower, and resisting fire.
You're totally right, fire is way more powerful than it seems at first. I'm glad you picked up on that, I was wondering after my kiddo playtested how many others would neglect fire entirely and try to win by just smashing. I appreciate you taking the time to give feedback, thanks for playing my game!