It Came from the Nightosphere

 

Nightosphere is the third episode of Adventure time's second season. Very little is known about it at this point, aside from a few things confirmed by the production staff.

characters

 * Finn
 * Jake
 * Marceline (confirmed by Phil Rynda)

Trivia

 * Originally this episode was called "return to Nightosphere"
 * This is apparently Pen's favorite episode of the second season.