This is really awesome! Super stylish and a really creative and interesting idea for a deck-builder. It's a little janky to drag the cards into the places you want, but that's fine (Also, not sure if you already know this- if you lose and then try another run, you keep the same deck that you lost with).
I see a lot of people commenting that they really didn't understand how the game worked at first- and I was in the same boat lol. It wasn't until after I randomly beat the first enemy, then was forced to cut a card in the second fight that it actually clicked with me. I wonder if having the first initial fight have something other than 3 actions (Like 2 maybe), before you even get prompted to add any cards to your deck would help with this. That way you'd be forced into understanding the cutting mechanic.
Again though, the concept is really cool and all the animations are super satisfying. Really good job!