This was really cool! The gameplay was actually pretty fun once I got the hang of it, and the graphics and sound was very fitting. Honestly, my only criticism is something that I feel like is only a problem because it's a jam game. Right now, you kind of get a bit of information overload at the beginning where you're trying to get the hang of swapping troops and understanding what all the different cards do and how they work, and I also didn't understand at first that my opponent also had the same cards as me and was using them. I think if you were going to do a post jam version, having multiple levels where all the mechanics were slowly introduced would make it a lot more accessible, but also I get for a jam game you don't want to have the beginning go too long.
So overall, I think this is a really cool and fun concept and I think it has really great potential to be expanded into a full release. Very good job!