He is Batman's greatest nightmare come to literal life. The Batman Who Laughs is Bruce Wayne from a world in the Dark Multiverse where he has been infected with The Joker's nanotoxin. Possessing a mind capable of thinking like both Batman and his greatest nemesis the Batman Who Laughs has risen to a higher power than any mortal before him.
From Earth -12 comes the bloodthirsty Merciless, a nightmarish fusion of Batman and Ares. Clad in blazing armor and wielding the God Killer sword, this member of the Dark Knights is a supremely powerful warmonger, taking all of the best tactical skills of Batman and pairing them with the might of Ares.