Khyber, the Dragon Below, embodies the Under dark, an endless labyrinth spreading below the world. Narrow passages worm through earth and stone, opening onto echoing chambers and bottomless pits. In the silence lie sunken cities, reclaimed by the earth and undisturbed for millennia. In the depths, seas of molten rock crash against melting walls, spewing poisonous gas and deadly eruptions. But although Khyber is dangerous and unforgiving, it too has life. The depths are home to strange beings—undead thralls sacrificed to unspeakable entities, hordes of monstrous beasts hungry for flesh. Nightmares are given form here, remnants from times and wars those who brave its depths, great rewards await.