Several square mile-long cavern lined with deep crystal all along the walls and ceiling.
NE1: Entrance. 36 dark chitinous huts line the semi-circular edge of the western part of the cavern. Each hut holds mining equipment for a team of 4-6 "Duergar" to dig tunnels in their respective location, digging straight out in at slightly different angles from each hut. A minimum of 1 duergar remains int he hut at all times, stationed to detect any sentience which crosses within 300 feet of the tunnel entrance from the other side.
The tunnels are circular about 5 feet in diameter. Many were made with the aid of a Purple Worm under the thrall of the Nexus Encephalon
About a square mile of wide open space, which is home to the errant Intellect Devourers and Duergar thrall, leads to the city walls.
Enemies: Several hundred Intellect Devourers
NE2: The Ruins of Uldrazim. The ruined city of Uldrazim is a long-abandoned Duergar city with a castle-fort stationed amongst a stone brick town, all behind a 20 foot high wall on the western edge of the city. To the north is the trades district, with blacksmiths, apothecaries, and libraries. Specifically, the Granite Codex is here, and is used by the Nexus Encephalon as one of several repositories for their stolen texts and histories on world religions, the Deities, and the Ends of Empyrean. To the south is the residential district, where most of the Illithid population has taken up residence, converting homes into tadpole spawning grounds and holding areas for prisoners and slaves. The castle is in the center, and is used as another stronghold of stolen texts, as well as all the magical artifacts.
Enemies: Mind Flayers, Eaters of Knowledge, Intellect Snares
NE3: Velkrazar, the Psychehold Ziggurat. Beyond the ruins, near the back of the cavern, is the ziggurat Velkrazar. Observed atop the ziggurat were four circular pillars with massive (15 feet tall) red deep crystals nestled in crown-like tops to the pillars. Open archways lead inside the ziggurat from each layer, and stairs run up the center of each side at a 45 degree angle.
Enemies: Nexus Encephalon, Dismalaravas, Eaters of Knowledge, Intellect Snares