Joker: Last Laugh was a six-issue miniseries which supported the Joker’s Last Laugh crossover event, which itself included special tie-ins for every other ongoing series at the time. It featured the Joker taking control of the world’s super-villains with Joker Venom, turning them all into cackling maniacs completely obedient to him.
Wonder Woman is featured only as an impersonation by Lady Spellbinder in this issue.
Oracle blames herself and Nightwing for the situation at the Slab, where the Joker has started a full-scale riot and ‘Jokerised’ most of the prison population. Shilo Norman and Dina Bell are trapped inside, and have to fight their way out through the Aqua-Block, which houses such man-eaters as Orca and King Shark.
Meanwhile, the Joker sets the next stage of his plan in motion, priming Black Mass to cause a devastating chain reaction which sucks the prison into a black hole. Batman and Nightwing, newly arrived on the scene, are warned of this plan by the Black Canary, and the three are helped to escape by Blue Beetle.