Noctica
Imagine a darkness so complete that it makes a night sky look positively bright. The darkness of caverns brings a strange kind of peace, and Noctica is all the more so because outside the keep’s walls rages a fiend-on-fiend battle that’s more intense, ferocious and desperate than even most Blood War battles. This thrice-walled mansion complex could be of any size — maybe its master, the tanar’ri Daisim, changes it at whim, or maybe nobody’s ever stopped to map it — but it’s large enough to hide the reticent lord rather well.
Noctica itself is said to be a comfortably furnished home, not unlike a palace, with servants and less savoury entertainments. It’s all plunged in total darkness, however, so a blood’s never sure exactly what the waiter serving him could be. That’s part of the fun for Daisim, but it certainly unnerves his infrequent guests.
Unusually for Abyssal Lords, the mansion of Daisim is open to any cutter who stumbles in, and the Lord of the mansion can even be quite genial. Annoy the basher, however, and you’re in for the fright of your life…at a moment’s notice Daisim and his fiendish staff can turn from perfect hosts (for the Abyss at least) to vicious and violent psychopaths intent on rending their would-be guests limb from limb.
This is the only known site on Molrat, the interdicted 11th layer of the Abyss. If you’re sent on a diplomatic mission to Noctica, then firstly: Try and get out of it. But if you can’t, then be very, very careful not to annoy the locals, berk!
Canonical References: Planes of Chaos Abyss Poster [2e] (brief layer description)
Source: Jon Winter-Holt, mimir.net