Really cool and well done. I'm finding it brutally hard right now. Maybe a little more explanation in the description?
As I play I'm slowly figuring out that there is a lot of information built into the display, but it took me a while and I'm still not sure I totally get what's going on.
Edit: Oh, there's a help page!
Edit 2: It seems like I lose attack and defense each time I move a card (regardless of demon clock). This doesn't seem to be mentioned in the help page (which is very nicely done).