Lex Luthor
When Superman tells Lex Luthor that he's supposed to be in jail, Lex Luthor states that the evidence did not hold up. When Captain Marvel reveals the origins of Dark Kahn who is partially made from Darkseid, the Kombat Rage overcomes Lex Luthor who blames Superman for his part in Dark Kahn's creation. Captain Marvel ended up calming both of them down as the villains call a truce with the Justice League. Lex Luthor takes Catwoman to secure the portal technology while Deathstroke and Joker serve as a diversion for some of the "invaders." Lex Luthor then goes after portal technology that belongs to the Mortal Kombat universe (defeating both Scorpion and Sub-Zero on the way) and is confronted by Jax (who has apparently faced him before, as Jax mentions arresting him). After taking down Jax, Lex Luthor ends up fighting Flash (who had defeated Catwoman). When both sides of the characters from the respectful universes meet up, Dark Kahn uses the Kombat Rage to make both sides fight with a shot of Lex Luthor fighting Jax again. With some of the opponents on both sides defeated, Lex Luthor (still consumed by the Kombat Rage) still blames Superman for Dark Kahn's creation and ends up fighting Superman only to be defeated.