Supernatural: Reclaimed

Castiel is gone and the Leviathans are out. The creatures that no one knows anything about are running rampage through the country and they're just getting started. With one of the Winchesters in utter devastation, everyone knows that if they don't do something, the world will end as they know it. Soon, the three Winchesters find an unlikely ally that is willing to help them bring down the beasts and send them back to where they came.