Smallville :

The aftermath of Doomsday's attack on Chloe and Jimmy's wedding leaves Clark in shock, but before he can search for the kidnapped Chloe, the Persuader appears and attacks him. Rokk, Imra and Garth, a trio of superpowered aliens also known as the Legion, step in from the future to help vanquish the Persuader, and the group realizes Brainiac has taken over Chloe once again.

Meanwhile, up at the Fortress, Chloe, as Brainiac, informs Davis he is Doomsday and was created to kill 'the other Kryptonian' and destroy the world. He tells Davis that he will soon become the creature permanently, and places him in an ice cocoon for the metamorphosis. The Legion inform Clark that today is the day he is supposed to destroy Brainiac for good, but the only way for him to do that would be to kill Chloe. Brainiac begins sucking the knowledge from every human mind through the world's computer network but he is attacked by the Legion. Before the Legion can kill Chloe, Clark intervenes and convinces them to focus their powers and pull Brainiac out of her. Afterward, the Legion takes what is left of Brainiac with them back to the future to reprogram him into Brainiac 5.