Joker has finally killed the Batman!!!
He needs something to entertain him, so he decides to attack the Justice League. He's going to take all the time he needs, but he'll be done in less than 6 months.
Can he take the League?
For those who can't read context
Joker has 6 months prep
League (Pre-52) consists of the original members excluding Batman = Wonder Woman, Martian Manhunter, Superman, Green Lantern (Jordan), Aquaman ( No water hand) , Flash (Barry)
After he killed batman he took his computer and he knows the league members identities.