Hey, just finished trying out this demo. It's honestly very fun to play. I love the concept of a Vampire Survivor + The Binding of Isaac mashup. This has the potential of having cool synergies and more spells to make an incredibly fun experience.
My only criticism would be that the wizard's collision seems a bit funky. I'm able to collect pickups with my head, but I would expect the collision to be at the foot of the player. I think that is more natural on a top-down bullet hell game.
Congrats, this is a very fun concept. Honestly I'd love to make a game with this concept myself, looks simple and very fun to make. Good luck on your project!