Neat little game, and I liked the combination of switching element when taking damage and the ability to target either yourself or the enemy. I also liked the art style: simple but pretty, which made it easier to pick up for me (because sometimes there's too many things drawing attention and it becomes a bit overwhelming).
Although I didn't really understand the "UNEFFECTIVE" when a 3 and a 4 lightning canceled each other out. I.e. I was fire, they were water so I figured we both could take electric damage.
Also, the "End Turn" button seems redundant if I can't change the card once placed. And I very much couldn't do that, because trying that broke the game. I also broke the game accidentally by clicking off screen and back another time, which is unfortunate.
Lastly, it could benefit from some background music. And the AI was a little easy, but that's also okay for a jam - it makes it more approachable for a one-time play and a big audience.
Here's some shots from my playthrough: https://imgur.com/a/loD9Dw3
Great job!