In the final act of “Justice League,” the superhero team, consisting of Batman (Ben Affleck), Wonder Woman (Gal Gadot), Superman (Henry Cavill), Aquaman (Jason Momoa), The Flash (Ezra Miller), and Cyborg (Ray Fisher), comes together to stop Steppenwolf (Ciarán Hinds) from unleashing a destructive force known as the Unity.
The Unity involves the combination of three Mother Boxes, ancient devices of immense power. Steppenwolf aims to use the Mother Boxes to reshape Earth into a nightmarish apocalypse similar to his homeworld. The Justice League must prevent the Unity from happening to save humanity.
Superman, who was presumed dead after the events of “Batman v Superman: Dawn of Justice,” is resurrected with the help of the Mother Box possessed by Cyborg. Initially disoriented and in conflict with the other heroes, Superman eventually regains his senses and joins the fight against Steppenwolf.
In the climactic battle, the Justice League confronts Steppenwolf in a final showdown. Superman’s return proves pivotal, and the combined efforts of the heroes lead to Steppenwolf’s defeat. With the Unity disrupted and the threat averted, the heroes disband, but not before acknowledging the need for their alliance in the face of future threats.
The film concludes with a glimpse of Lex Luthor (Jesse Eisenberg) escaping from Arkham Asylum and receiving a visit from Deathstroke (Joe Manganiello), hinting at the formation of the Injustice League. Additionally, the movie features a post-credits scene where Superman and The Flash engage in a friendly race, showcasing the camaraderie among the heroes.
It’s important to note that “Justice League” underwent significant changes during production, including directorial shifts from Zack Snyder to Joss Whedon. The film’s reception was mixed, and subsequent developments in the DCEU may have expanded or altered the narrative. For the latest information, it’s recommended to check more recent sources.