Lucifer tries to dissuade Michael from the fight, saying it is one of God's tests, and they have no idea what the right answer may be. He suggests they walk away. Michael counters that he must carry out God's orders, and that it's his destiny to kill Lucifer, who is evil. Just then Dean arrives in the Impala, Def Leppard's 'Rock of Ages' blaring.
Dean tries to talk to Sam, inside Lucifer, but Michael tells him it's not his fight anymore. Castiel arrives, tossing a molotov of burning Holy Oil on Michael, banishing him temporarily. Lucifer turns and disintegrates Castiel, and then as Bobby shoots him, he snaps the hunter's neck.
Lucifer beats Dean, taunting him, saying he will kill him slowly and make Sam feel it. Dean doesn't resist, but tells Sam he won't leave him. As Lucifer prepares to land another blow, he glances at the Impala, and suddenly all Sam's memories of life with Dean rush at him, allowing Sam to take control from Lucifer. He tosses the Horsemen's Rings to the ground and recites the incantation to open Lucifer's Cage. He and Dean look at each other one last time. As Sam goes to throw himself in, Michael reappears and tries to stop him, but but is dragged in with Sam.
As Dean grieves, broken and bloody, Castiel, his life and powers restored, reappears and heals him. He also resurrects Bobby.
- Chuck Shurley predicts that this ground will host the final confrontation between Michael and Lucifer because everything must end where it began. 
Stull Cemetery is a real cemetery in Stull, Kansas about 40 miles from where Sam and Dean were born in Lawrence, Kansas. It has a lot of lore associated with it, including that it may be a gate to Hell.