Board Thread:Spoilers!/@comment-413929-20151029063935/@comment-26549743-20151105163930

I don't know how farfetched this is, but part of me feels like maybe they've opened a portal to the Underworld in the midseason finale to do something (such as maybe trying to throw the darkness itself into the Underworld so it can't latch onto anyone anymore) and then opening the portal to the Underworld causes literal Hell in Storybrooke, especially since notable dead villains like Cora and Pan will be in this episode.