Batman is discovered amongst the ruins of Metropolis still alive inspite of his greivous injuries. Brought to a hidden sanctuary his body is rebuilt, however, it is revealed that Luthor has been munipulating events.
As Batman awakens just as Brainiac's Enforcers discover the sanctuary, he makes his way to the Fortress of Solitude to activate one of Rip Hunter's Time Portals to support Luthor's plan of building a metahuman army using the stolen Exobyte data. However, Luthor betrays him and enters the portal as Brainiac's forces invades the fortress.
"We're not done. This is just the beginning." — Batman