Location from A Practical Guide to Evil by ErraticErrata
The underground drow kingdom — a realm of eternal darkness where the Mighty kill each other for Night, ruled by twin goddesses who turned murder into a religion and a power system.
The Empire Ever Dark is the drow's underground realm, ruled by Sve Noc through Night. The drow were forced underground ages ago and developed a culture of competitive murder: the Mighty steal Night from those they kill, creating a hierarchy where power literally flows from violence. Catherine traveled here in Book 4 to recruit the drow against the Dead King. The drow were facing genocide from expanding dwarven kingdoms and accepted her offer of alliance. Their migration to the surface — an entire civilization seeing the sun for the first time — is one of the series' most striking images.
Underground — vast caverns lit by bioluminescent fungi and the glow of Night. No sun, no sky, just the weight of the earth above and the darkness that the drow have made their home. The architecture is alien and ancient, carved by a civilization that has lived without light for millennia.
Also known as: Empire Ever Dark, the Everdark, Kingdom Under