Really good game!
It plays really well and was entertaining. The art style is very nice and I like the idea of burning the cards. Do I use the great card again but then the card is gone or do I try to keep it to use more often. This could lead to some interesting decision making in the game.
Even though I really like the art style it looked a bit weird because the pixel size of the enemies looked different than the one of your backpack and also different than the status icons next to the health bar. The health bars could a need a bit more detail. They did not match the art style.
I noticed some bugs like missing tooltips for a card that looked like a shot gun but nothing that broke the game or make it crash.
Now I will try to beat the boss again. Cool game. Well done!