Cool game! I really like the idea of a tower defense deck building game and had a fun time playing. It took a few immediately lost attempts to figure out the mechanics of the game so I think a tutorial would definitely help. Once I got the hang of it though it was really smooth for the first three levels. I do think the balance may be a bit off because it seems to ramp up a bit faster than you can reliably get enough units on the field, but maybe I was just unlucky! Nice job :)