Emberhold

The Emberhold is the capital of the Duergar forces in the Underdark. The city is described as a cluster of building punctuated by seven black obsidian spires. The spires themselves are outfitted with several ballista with duergar guards patrolling along carved tiers. In the center of the city is a massive, ebony fortress, upon which magma flows from the top of the cavern, and is guided down along the side of the fortress into a moat.