or the Joker, who has yet to appear in Battle of the Cowl yet.
It's not really the Joker's style to let someone else take the credit for the crimes he commits. That said, however, I must admit that the idea isn't without precedent. Dini just recently had Joker pretend to be a magician. And the Joker is likely to be even more unhinged than usual after the death of his rival, so who knows what he's up to?
I generally default to thinking that Black Mask really is just Black Mask, since we all know that consistent continuity in comics is just a myth.