This is a neat, minimalist take on the roguelike deckbuilder genre (though we don't really deckbuild so much as deckplay). I wish I had a clearer sense of enemy remaining HP so I could make more informed decisions about who to attack with how much damage. I also would love a block or something similar so that I had some recourse when all the enemies decide to attack simultaneously.
The graphics and audio do a lot with a little here. I found the slight hang after playing a card to feel a little jarring, some kind of animation, effect, or something feels warranted or else it just yanks me out of the experience.