I think I used up the two coins I got at the start and never got any more back D:
It's an interesting take on Battle Network-type combat, but it suffers from lack of things such as health bars and even which of of the four cards are currently being played. I mostly understood the attack range of each card, but it could have been better to put that at the top of the card, as it was almost hidden by the edge of the screen. With cards, it's preferred to be able to see important things from a glance (in this case damage and range).
It could turn out to be a very interesting title if it had more time in the ovenm which isn't always a possibility with game jams, but an idea if you want to continue development afterwards.