austere forge
It seems a joker cloned by invisible joker sometimes defaults to using the Red Deck back, which of course usually isn't visible, but is evident when fighting Amber Acorn. Deck is Zodiac, if that's relevant.
I'm fairly certain the red-backed card is Drunkard, which I copied with Invisible Joker earlier, though I suppose I can't say for certain it was the copied one since Drunkard doesn't activate per-se.
