Citadel of Thought

The Citadel of Thought was the divine realm of Deep Duerra. It was located in the Thuldanin layer of Acheron according to the Great Wheel cosmology, while in the World Tree cosmology it was considered to be part of Hammergrim.

Cosmography
According to the World Tree cosmology, the Citadel of Thought was a hall located in the courtyard of Hammergrim.

Inhabitants
The underground of the Citadel of Thought contained vast catacombs composed of fiery tunnels, populated by ember guards made in Hammergrim whose job was to torture any duergar who had offended Deep Duerra in some way.