Supernatural Episode 10.23 Brother's Keeper

Dean continues to hunt, but the Mark affects him to the point that he gets another hunter killed. Realizing he's gone too far, Dean summons Death (Julian Richings) to kill him before he hurts anyone else. Death explains that the Mark is the lock on the prison of an ancient evil called the Darkness and if the Mark is removed without being passed on, the Darkness will be released. He agrees to transport Dean far away in exchange for him killing Sam so Sam won't try to rescue him. Dean calls Sam and explains that he feels that they are evil and ridding the world of both of them is for the greater good. Sam eventually agrees, but reminds Dean of how good he is and his love for his family. At the last moment, instead of killing Sam, Dean turns Death's scythe on its owner, killing Death instead. At the same time, Rowena agrees to remove the Mark from Dean's arm in exchange for her freedom and Castiel calls on Crowley to get the necessary ingredients. One of these proves to be a young man who Rowena cares deeply about and she has to sacrifice for the spell. Unaware of the consequences, Rowena casts the spell and the Mark is removed, but she escapes, casting a spell on Castiel that causes him to attack Crowley. With the Mark gone, the Darkness is released into the world and washes over the Impala as the Winchesters desperately try to escape it.