The CW has released an official description for the December 9 episode of Supernatural, airing on December 9.
The episode is called “O Brother Where Art Thou?” and here’s the write up.
AMARA UNLEASHES HER POWER UPON THE WORLD — Amara (guest star Emily Swallow) unleashes her power on the local townspeople as she issues a shocking challenge. Dean (Jensen Ackles) tries to better understand the hold Amara has on him, while Sam (Jared Padalecki) and Crowley (Mark Sheppard) come up with a plan that could have disastrous consequences. Robert Singer directed the episode written by Eugenie Ross-Leming & Brad Buckner (#1109). Original airdate 12/9/2015.