Dark Nights: The Batman Who Laughs #1

Synopsis

On Earth -22, Batman has a final confrontation with the Joker that ends with Batman killing the Joker. However upon his death, a virus is released from his body which infects Batman. As a result, Batman's mind becomes evil and twisted like the Joker, leading him to murder all of that world's other heroes. After conquering his Earth, he accepts the invitation of Barbatos to travel to Earth 0 to help bring that world into the Dark Multiverse.