I like how the card flips every round, making it so that you basically need to build two decks at once and balance out the enemies with the buffs and attacks. The spike attack animation is definitely my favorite of the bunch but overall the aesthetic is all very nice already.
If you are looking for ideas on how to expand the game after the jam, might I suggest more negative cards other than enemies, like debuffs or something that alters the level with more hazards for example. Something like that could help increase the difficulty a bit.
Also a brief description of how an attack/enemy works when looking at the card could be nice to help new players, and eventually sfx and music would really bring the game to a whole new level.
Also, my cards started going offscreen as I progressed, but that's only because I was playing for so long that they literally couldn't fit anymore lol.
Anyways, this was a great entry for the jam and I see a lot of potential with further updates. I'm excited to see what you do next!