Batman has decided that the Justice League are a potential threat to earth, he secretly forms up a plan to eleminate them. He must Kill Superman,Wonder woman,Martian Manhunter,Green Lantern and the Flash and incap and imprison the rest. And deystroy there space station.
The Justice League are unaware of Batmans plans
Batman has 5 years of prep to build himself a special exoskeleton to protect himself and to create some gadgets to help him eleminate his foes.