It was a very fun experience! Like the first comment said, I found there were a lot of cards picking on level -1. But at one point I got so broken I rolled over every other level, which was very satisfying. Until I bought a weapon and my character became worst in all stats. And then I improved again and rolled over every level, only to be worst again once I was facing the final boss. Is this intended?
All in all, it was very addictive, especially the feeling of utterly destroying everyone was very good.
Good work!