I like the rhythm for the spellcasting, has a pretty good flow after getting used to it. The more rewarding spell casts being harder is a really good take on the risk reward theme.
The core game of this is pretty fun, I think more spells that you could swap between loadouts of along with things like random items or upgrades choices that incentivise you to use different spell builds each time could be a really fun way to expand on this.
At first I didn't read about the block button, I was fighting for my life against that bat tanking every hit and spamming heals. Makes a lot more sense after knowing about the block