Khyber

Khyber is said to be the body of one of the progenitor dragons that created the world of Eberron. It is a subterranean world full of Fiends, Aberations, Daelkyr, and sleeping Overlords that were bound by the Dragons and the Gatekeepers.

Though Khyber can be accessed through the plain of Eberron in particular spots few but the fool-hearty choose to do so and these spots are well guarded by Draconic Guardians and the Gatekeepers to ensure that the Rakshasa and their Overlords don’t re-emerge and start the Demon Wars anew.

There are some dark cultists who worships Khyber in the form of the Dragon Below. It is said that she can bestow many dark wishes on her worshipers. Most often cultists of the Dragon Below seek to free beings (e.g. daelkyr, rakshasa rajahs, or demons) or gain power from those same beings through sacrifice or devotion. Cults to the Dragon Below are illegal in all areas where there are laws and most specifically in The Light of Siberys where the pull of Tiamat is said to be strongest.

WHAT DO YOU KNOW?
Knowledge (dungeoneering)
DC 10: Khyber is home to an astonishing array of deadly creatures. The vast majority of aberrations come from Khyber, and the underground world is also home to monstrous humanoids, giants, and magical beasts—from trolls to medusas and basilisks.
DC 15: Weapons formed from byeshk ore are effective against aberrations that shrug off the bite of steel, including dolgaunts and dolgrims.

Knowledge (geography)
DC 15: Below the surface of the earth, another whole world stretches out, vast in its expanse and uncharted in depth. This lightless world beneath the world is called Khyber, the Dragon Below.
DC 20: Any natural cave or manufactured tunnel might be an entrance to Khyber. New gateways to the Dragon Below appear constantly and unpredictably, but constant entrances are especially common near the west coast of Khorvaire.

Knowledge (the planes)
DC 15: A major planar incursion occurred nine thousand years ago, when an army from Xoriat attacked Eberron. Aberrations are either natives of Xoriat or creatures twisted by the daelkyr—the lords of madness who led the incursion. The Gatekeeper druids bound the surviving daelkyr commanders in the depths of Khyber, but the creations of the fleshshapers remain a threat to this day.
DC 20: You know the names of specific daelkyr and the other information provided on the following page.

Knowledge (religion)
DC 10: Khyber was one of the three progenitor dragons. Eberron bound Khyber in her coils; Eberron became the world and Khyber became the underdark. This deep, perilous realm is said to be filled with all manner of monsters.
DC 20: Khyber is said to be the father of fiends. The dragonshards found in Khyber have an affinity for binding spells, and legends say that many powerful demons are trapped in the underworld.

Khyber

Argonnessen: A Draconic Exaltation jenniless jenniless