This game, though short, was nice and fun!
There definitely were some bugs, like cards spawning over other cards, or card selections being visible when you hovered over empty space (where cards normally are if you haven't played them), but they didn't take away too much from the experience.
I did find that the squash/stretch was a little much in some places -- like the cards expanding at the bottom of the screen to the point where I couldn't read the Mana cost.
Overall though, I enjoyed it. Fun art, gameplay was simple but tight, and the secret ending was challenging. Nice work!