When I was younger, Luna, and later Nightmare, told me that there were things that lurked in the darkness, within the spaces created by shadows that even they would be wary of facing at their full power. And that they would be terrified to fight then with so much of their magic locked away by the seal that the Elements of Harmony had placed upon them centuries ago. Old things... Powerful things... But we took comfort in that such things existed only in Equestria. But, as we learned on that night so close to Hallowe'en when I was ten, we were wrong...

So very, very wrong...