'Enemies becomes allies and allies becomes enemies', the April 16 episode will see the collaboration of Zod and Clark.
Brian Austin Green returns to "Smallville" as the man with artificial heart, Metallo. In "Upgrade", Zod continues to pose as "The Blur" and asks Lois to investigate one of Tess' secret labs. An explosion rocks the lab, and Lois is rescued by John Corben, Metallo's alter ego, who was a subject of multiple experiments.
While investigating the explosion, Clark is exposed to red kryptonite. And infected Clark takes Zod to the Fortress. Tess turns to Chloe for help and they send in Corben to stop Clark from revealing all his secrets.
On another news, EW recently reported that members of Justice Society of America will return for the finale which date is not yet revealed. Black Canary was first confirmed, followed by Hawkman, Stargirl and Cyborg.