While we certainly know that the Batman v Superman: Dawn of Justice follow-up Justice League revolves around the formation of the titular team, led by Ben Affleck’s Batman, there also needs to be a reason to form said team. That reason comes in the form of the film’s antagonist, which thus far has remained (officially) a mystery, although a deleted scene from Batman v Superman certainly set things up rather nicely for the comics baddie Steppenwolf and this alien technology called Mother Boxes.