However, the Joker ends up tricking Superman into attacking Lois Lane, who was pregnant with Superman's child. This results in her death which triggers a nuclear explosion that destroys Metropolis. Superman murders the Joker and establishes a tyrannical government called the One Earth Regime. However, Batman, opposed to Superman's methods, forms the Insurgency to overthrow the Regime. With the aid of the Justice League from another universe, the Regime is defeated and the Insurgency works to rebuild. However, Superman's ally, Black Adam, finds Kara's ship and brings her to Earth. Together they free Superman's current lover Wonder Woman from imprisonment on Themyscira. Wonder Woman and Black Adam hide the tyrannical nature of the Regime from Supergirl and train her to use her powers in secret, though Brainiac attacks Earth after being alerted to Kal-El's survival due to his Regime's supporting the Sinestro Corps. in a war with the Green Lantern Corps. Supergirl and the Regime try to break Superman out of prison, but are stopped by Batman and his allies, though Batman decides to release Superman, calling a temporary truce between the Regime and the Insurgency to combat Brainiac. During Brainiac's attack on Metropolis, Supergirl witnesses Wonder Woman's brutal attack on their ally Harley Quinn after Harley tried to stop Wonder Woman from killing the Cheetah, as it violated Batman's no-killing policy. Supergirl saves Harley's life and confronts her cousin at the Fortress of Solitude. Supergirl is horrified to learn her cousin approves of Wonder Woman's actions, though he believes it would be best to deal with Harley after Brainiac is dealt with. Supergirl compares his methods to General Zod's and briefly fights Superman and his allies, though Brainiac's attack forces them to focus on dealing with him first. Superman and Supergirl work together to attack Brainiac's ship, but are stopped by its barrier. Brainiac destroys Metropolis reminding Superman of his past failure, causing him to attack the ship with all his might, only to be seemingly killed by Brainiac. Batman confronts the grieving Supergirl and reveals that Superman was once his friend. Believing Kara is the last surviving Kryptonian, Brainiac offers to spare Earth if they hand over Kara Zor-El as he wishes to study the effects of yellow sun radiation on Kryptonian cells, though Batman refuses. Batman, his allies and the remaining Regime members manage to overload the shields protecting Brainiac's ship. Batman and Supergirl manage to infiltrate the ship, but Supergirl is captured, though Batman discovers that Superman is still alive and the two join forces to defeat Brainiac and free Supergirl.