GREAT FUN, LOVED IT!
Healing is op af but I really had fun discovering it (It's basically infinite at this point, I got a bunch of healing enhancers in the low levels so there's no real incentive to finish a fight as hp remains between battles). Capping the max hp can help mitigate that:
Would love to try a strat for drawing your entire deck with a Mushroom and playing all of it with a Gem. Also, I wish there was a unique design for a final boss!
Minor bug, you can sneak in an extra card if you click very quickly.
Congratz!