Depending on how you explain how it works in the game, I think that is SUPER unique. I'm a little confused on how you would numerate the stats for major arcana. Unless the Arcana is the type of stat and the you use the +3, +2, +1 stat block numbers. I love the reversal idea, I think is would be interesting if you gained a new stat because of it that is the "shadow" version of the previous stat when it was upright.
I settled on "each arcana IS your stat", and when you reverse that arcana instead of "roll above" you gotta "roll below"
Son if you get the Devil (15), you'll beat any card below that number. If you reverse it you now can only beat any card above that number. There are some kinks to iron but I like this shape so far.