Agh, what happened, my saved position vanished! Same computer, same browser, same log-in, I haven't cleared any data. Logged in today and I'm back to 30 Data 0 Cells :( I was enjoying it too.
Okay, so this wasn't entirely playing random cards to win. I beat the Chaosmaster in 2 minutes by sticking a Pheonix in front of his Air Spirit, then casting Madness every turn afterwards.
Nice aesthetic. I have a criticism: Some of the later levels require rapid mouse movement, and of course if the cursor goes over the edge of the game border, you lose control. This is an unfortunate limitation of the format.
I also haven't figured out hardcore mode, as my snake seems to spontaneously explode no matter what I do.
I don't really like Tower Defense games, and I suppose there's nothing particularly original about this one - but for some reason I find Cursed Treasure pretty addictive. I think that the limitation of terrain types actually gives it strength.
I don't think that you have selected the hardest mode.