This was really good fun to play once I understood how to play. It's a shame that you didn't have time to get in some UI with tooltips explaining what things do and the card text was incredibly hard to read.
I definitely think this could be taken further and released fully. I would have given up in frustration at the point where I was just getting the same potion cards over and over without understanding why, but once I understood the core better I found it really enjoyable. watching the enemies spawn onto the map and instantly die was very satisfying.