User blog comment:KillRoy231/How did you feel about O Brother Where Art Thou?/@comment-1031724-20160127004748/@comment-1031724-20160127201618

It'll probably happen at the end of the season, plus Amara must win because the only way she can be defeated is to imprison her. Aside from the fact that it took God and all four of His archangels to do this last time (to which Raphael is dead, Gabriel is either dead or in hiding, and according to Lucifer, Michael is insane, so really we've only got God and Lucifer, who are currently enemies) someone has to get corrupted by the Mark of Cain to keep her imprisoned.

And the writers are so cruel as to kill our favorite characters. No matter how disappointed anyone will be when Lucifer dies, the disappointment of killing Castiel will be even worse.