Really loved this game! Reminds me a little of Puzzles & Dragons in all the best ways, where you feel so good for unleashing several spells at once. Really makes you want to replay the stage, getting a new build every time! Your addition of different starting spell sets is a genius idea for exactly this reason! My favourite is the hex build of course, really enjoyable to pull off.
All in all, great demo, wish you all the best on developing it to the end!