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(Abyssal realm)

Slime-choked immense sewer and cavern network
Source: Lords of Chaos, pg(s). 18, 41

The Undersump is the Abyssal realm of the demon lord Jubilex. The Undersump resembles a system of sewers for the Abyss; they run under numerous other Abyssal realms, contain a maze of tunnels and caverns, are connected to the River Styx, and are filled with detritus and slime.

Some creatures use the Undersump as a covert conduit between Abyssal realms, but must avoid being caught by Jubilex in the process. Due to Jubilex's inherent indolence and lack of care for his realm, however, parts of it are now claimed by others.12