Now i'm curious. If you use a 2 card and your ATK stat is 0 the damage will always be 2. Did you get a lot of clover aces?(seems improbable they're rare). Well the idea was to give more visual feedback to the battle and the sign at the first floor explains breefly some things,but ir really needs a better tutorial. I had no time to implement those things, unfortunately.
About cloves aces, I honestly don't know xD All few battles I had were quite confusing because of the reasons I described above, yet I don't think my "bugs" were pure luck - rather random lucky events and moments when I simply could not understand what happened.
You still did it well, it must be much more difficult to program it all using the platform you used for the development.