Supernatural (TV series)/Recap/S07/E17 Episode Seventeen

Season 7, Episode 17:

The Born-Again Identity
When Lucifer pays Sam another visit, he drives him to the brink, forcing Sam to enter a mental hospital. Fearing for his brother's life, Dean takes matters into his own hands, calling upon every hunter he knows. He receives the name of a healer from one hunter, only to find a familiar face waiting for him.

Tropes

 * Back from the Dead: Castiel.
 * Easy Amnesia
 * Enemy Mine: Dean and Meg.