Supernatural (TV series)/Recap/S03/E10 Dream a Little Dream of Me

Season 3, Episode 10:

Dream A Little Dream of Me
Sam and Dean have to rescue Bobby from the clutches of a creature capable of killing people in their dreams.

Tropes

 * Battle in The Center of The Mind
 * Dream Sequence: Literally--all three of Our Heroes share a dream
 * Evil Twin: Dean encounters a dream-version of himself that is what he fears he'll become in Hell.
 * Or Was It a Dream?: Everyone's awake and the monster is defeated, but the cut-to-credits is Dean's demon doppelganger snapping its fingers.