This game is really amazing, and I hope it will see many updates with more characters, cards, enemy types, items, et cetera. It's honestly maybe the most fun turn-based tactical roguelite I've played since Through the Breach.
I do, however, have some feedback:
1. Status effects and keywords need to be more clear. Not knowing what Free Play or Ice does is a big deal when you're considering which upgrades to pick.
2. You should be able to check more in-depth explanations for your own attacks and the enemy intent in-game. Even though you'll quickly learn by trial and error, players may feel cheated when they don't realize certain enemies have Swirl attacks or Free Play effects or Double Strike. Just being able to check in-game is convenient, otherwise people will feel like they've been tricked, or they'll just manually make notes.
3. I feel like there should be a "skip upgrade" button, or maybe some sort of basic minor reward to pick if you don't want the upgrade and don't want to/can't afford to reroll. Many times, I've just felt like my build can't afford to put +2 cooldown on an attack just for a Poison effect.
4. One incentive to get players to pick status effect upgrades such as Ice, Electric or Poison could be to add support or synergies to make them stronger. Perhaps items that increase damage, potency or duration? If I could get an item that made Electric effects bounce farther so I could make a dedicated Electric build, that would be really cool I think. This is more a suggestion than feedback, though.
5. The First and Third boss are really easy to cheese with Smoke Bombs if they have low enough cooldown. I've repeatedly been able to create an infinite loop where they cannot attack me, but I can deal damage to them. If you want this in the game, I don't mind it, but I thought I should make you aware of it anyway
I hope this feedback is helpful, because I really like the game so far and I hope you continue to improve it even further :]