here are some thoughts that came to mind while playing
UI:
-in the character selection screen why do I need to undo the selection before I can click on another character?
-the quit to main menu button is difficult to find
-you could grey out unclickable cards, and highlight the end turn/draw buttons when no card is clickable
-the constant highlight on some UI elements is a bit misleading. to indicate the turn player I think it would be enough to only highlight the character icon
GAMEPLAY:
my biggest problem with the overall experience was that the suitable (heh) amount of game actions and decisions you take doesn't translate well to actual player agency. for example I was playing against a slime, and after a reshuffle all that changed compared to the start of the battle was that I lost some hp. this retroactively makes the player feel bad about his input not having weigh, and makes the battle feel very slow and sluggish because there's no strong sense of having made progress after a reshuffle. on the bright side I don't think that this is something you can only fix through revisiting the game mechanics, you can probably just tweak some numbers (like buffing damage and hp while keeping the heal constant) and add some more difficult to recover from skills. maybe, to really make sure that there's no matchup where neither player can progress, you can make an alternative wincon in this manner:
- every shuffle starts a round
- after a reshuffle the player that lost less hp wins that round
- the battle can also end if one wins 2 rounds