Nice game, congrats! I went until the third level, lost with only one enemy left with 4hp T_T
In the first levels it is understandable, but perhaps it would be better to control a little the randomness in later levels to prevent the player from having 5 identical cards, as this takes away some of the choice.
I also though at first the game would be a lot slower because of the -5 att consequence, but you got around it with the beam card. Nice thinking. :D