On this episode of Supernatural…
Crowley retrieves the Horn of Joshua.
Crowley calls on Sam and Dean for help to exorcise Lucifer from Castiel and then he will give them the weapon.
Sam wants to summon Lucifer and give him the weapon to defeat the Darkness before exorcising him.
Rowena survived her death with magic and helps the Darkness recover from her wounds.
Lucifer tries to recruit the angels in Heaven.
Sam, Dean, Rowena and Crowley summon Lucifer.
They attempt to contact Castiel to get him to expel Lucifer.
Crowley even enters the vessel to wake Castiel, but he fights Lucifer.
The magic fades and Lucifer takes the horn. He starts to kill Sam and Dean before Amara shows up.
He uses the weapon on her, but it doesn’t work.
Amara takes Lucifer and plans to use him to lure God out of hiding.
Crowley and Rowena run away.
Sam and Dean realize perhaps Lucifer isn’t the right person to use the weapon. They plan to try and get Castiel back.