I'm looking for a story starring King Sombra. The plot is as follows: Sombra returns around the time of The Chrystal Empire Part 1 and takes over the Chrystal Empire, but nobody from Equestria comes to stop or overthrow him. He's confused by this and sends his minions to investigate, only to find that everyone in Equestria has mysteriously vanished. This makes him worried, so he does everything he can to find out what happened to everyone while still running his empire. So... Has anyone seen it?