It seems as if the world is constantly in chaos. From Lucifer being freed from the cage and put back in to the Leviathans being freed from Purgatory, you would think that the world has been through enough and things could never get worse but you'd be wrong.
Metatron had tricked Castiel into causing all Angels to get cast out of heaven, causing them to fall from heaven. Many of them have died from the fall while others have to figure out how to get back in heaven because not only did the spell cause them to fall but it also closed the doors of heaven, causing them to not be able to get back in. Thinking it was all Castiel's fault, they are out looking for him, hoping to get revenge against him
I'm sure you think that there is no way it could get any worse than that but you couldn't be more wrong. While Sam never did complete the trials, finding out that it would kill him, Crowley was able to find out the spell to release all demons from hell, letting them take over the world, causing hell on earth quite literally. Because of this, there is a war going on on Earth between Angels and Demons. Will the hunters be able to stop them or will this be the end of the world once and for all?