Almost a year after Celestia's great crusade against necromancers concluded, Mortem discovers a rather large army outside his castle. Not wanting to cause an incident, he works towards a diplomatic solution.
Some ponies think Diamond Dogs hoard gemstones for the same reasons ponies do. Others think they eat them, like dragons. If ponies knew the truth, they might not be so eager to rob them of their subterranean treasure. If only they knew.
The horror writer was looking for old magic, something that prophecies, miracles and princesses hadn't touched yet. What he found instead was a strange filly in need of his help.
When Princesses Celestia and Luna visit a public art gallery, they come upon a painting of Celestia, banished to the moon. They react to this in the only reasonable way: artistic criticism and analysis.