Very clever, Mr. Busiek. A little too clever. But you've tipped your hand with the anti-matter Earth.
I see who your "Enigma" is. He's Quizmaster, the anti-matter Riddler.
We've already seen the anti-matter Earth "revise" certain details to reflect DC-Earth. In your JLA run, Power Ring was "revised" from a white man to a black man to reflect John Stewart's membership in the League.
And since on DC-Earth, the Riddler is nominally a good guy these days, then Quizmaster must be a bad guy. And those burns on his face were no doubt caused by the Qwardian invasion.
Well played. Now let's have Gravedigger's grandson show up again.