The CW released a few clips of the episode
8.23 - "Sacrifice".

With Kevin’s help, Sam & Dean bound into one last play against The King of Hell.

Airs: Wednesday, May 15th, 2013 at 9/8c

The CW has released episode stills of
8.23 - "Sacrifice" (Season Finale).
Metatron initiates a plan with Castiel to take on the bureaucracy of Heaven.
Written by: Jeremy Carver,
Directed by: Phil Sgriccia.
Airs: Wednesday May 15th, 2013 at 9/8c.

The CW released a few clips of the episode
8.22 - "Clip Show".

Sam and Dean reunite with Castiel. Meanwhile, Crowley digs into Sam and Dean’s past.

Airs: Wednesday, May 8th, 2013 at 9/8c

The CW has released episode stills of
8.22 - "Clip Show".
Sam, Dean and Castiel stumble upon a film which could be the key to the third trial.
Written by: Andrew Dabb,
Directed by: Thomas J. Wright.
Airs: Wednesday May 8th, 2013 at 9/8c.

The CW released a few clips of the episode
8.21 - "The Great Escapist".
Sam and Dean make a discovery that sends them to a casino in Colorado, to find a mysterious recluse who may be able to help with the third trial.

Airs: Wednesday, May 1st, 2013 at 9/8c

The CW has released an official description of
8.23 – "Sacrifice".
WHAT MUST SAM, DEAN AND CASTIEL SACRIFICE TO FOREVER SEAL HELL?
Written by: Jeremy Carver,
Directed by: Phil Sgriccia.
Airs: Wednesday, May 15th, 2013.