On the season finale of Supernatural…
After Dean attacks Gadreel, Sam and Castiel lock up Dean.
Dean calls on Crowley to get him out, reunite him with the First Blade and hunt down Metatron.
Castiel teams up with Gadreel to try and sneak into Heaven to destroy the angel tablet. They are captured by the angels, but Gadreel blows himself up to convince them that Metatron is fooling them all.
Metatron is pretending to be the new Messiah, performing miracles.
Sam agrees to let Dean use the First Blade, but Metatron overpowers Dean. He stabs him and kills him.
Sam and Dean reconcile their argument. Sam decides to summon Crowley to bring Dean back.
Crowley reveals that he didn’t tell the whole Cain story. Dean awakes a demon.