Really fun game, quite impressived how you made it in 48 hours!
For a little feedback, at first I found weird how you select an enemy before using the card; it seems more natural to choose a card then a target (this is really minor) and how your extra energy resets between rounds. Bugwise, The only thing I noticed is that you can play cards from the deck (that do nothing and you draw them from the discard pile).
TBH, It would be interesting to see this as a full game.