This article is about the subterranean realm. For the dragon, see Khyber.

Khyber is said to be the body of one of the three Premiers Dragons that created the world of Eberron. It is a massive subterranean realm that is filled with lesser fiends, Aberrations, Daelkyr, and sleeping Rajahs that remain bound by the Prophétie Draconique and the sacrifice of the Couatl that kindled the Flamme d'Argent during the Âge des Démons.

One of the regions of Khyber is the Vault of Le Geolier, where souls taken by Keeper's Fangs are believed to be delivered. There, an ancient Draconique Lich claiming to be Le Geolier lords over these souls and inflicts hellish suffering upon them.

Khyber seems to be a composite of the D&D idea of the Underdark and certain traditions that place Hell, literally, underground.

RISING : KHYBER I n Khyber, you could … • Fight Flagelleur mental and armies of hideous aberrations. • Discover a wondrous realm lit by an inner sun. • Prevent a fiendish overlord from escaping its ancient prison. The Commun creation myth contends that when the Progenitor Dragons fought, Eberron trapped Khyber in her coils and became the world, imprisoning her evil sibling in a living prison. Bound within the world, Khyber spawns Démon and monsters to plague the children of Eberron. This might be myth and metaphor, but it's also a description of fact: there are worlds within the world, realms inhabited by aberrations, fiends, and all manner of monsters. Any time someone descends below the surface of the world, they enter Khyber. But the underworld takes two very different forms. First is the natural realm, networks of tunnels and caverns formed from stone and soil. These passages are dark and dangelrous, but they're exactly what you expect to find in an underground realm. Such passages might be home to carrion crawlers, Géant beetles, or clans of kobolds. But ultimately these mundane caverns follow the laws of nature. There's another aspect to Khyber: go deep enough and you find a seemingly endless array of demiplanes, each stRanger than the last. When descending into a chasm, you could find a Labyrinthe inhabited by Démon or discover a realm consisting of the guts of a colossal living creature. Anything is possible in Khyber, and these “worlds within” are home to all manner of terrors. The demiplanes of Khyber are not concretely tied to the world above. You could discover a passage in Breland that leads into a disturbing subterranean swamp filled with oozes and slimes. After traveling what seems to be a few miles, you might emerge from a different tunnel in Xen'drik, half a world away from where you began. The Bastions de la Nation Démontrate this mystery. Over the past century, the Nains discovered a vast subterranean kingdom within the Monts Ferreux. Most of these halls rest in the natural layers of Khyber. The halls connect to one another in logical cartographic order. But as the ancient Nains dug deeper, they opened passages into the unnatural realms and unleashed the hordes of the daelkyr Dyrrn le Corrupteur. Passages to Dyrrn's realm also exist in the Frontières de l'Ombre, on the opposite side of Khorvaire. The Corruptor's domain doesn't necessarily stretch across the entire world; the portals to the worlds within defy natural law. These connections impact the world in a number of ways. Dark forces can rise anywhere in the world, bursting out of a previously unknown portal to Khyber. This fact dictates the primary mission of the Church of the Flamme d'Argent: to stand ready to defend the innocent from such unnatural threats. Because the demiplanes connect to the world at random, you never know what you might find when you venture into the depths. A newly opened chasm in the sewers could be an entirely mundane hole in the ground, or it could be a passage to the Abyssal Forests of Khar. The many layers of Khyber share similarity only in their strangelness and deadliness. Eberron is the natural world; Khyber is the source of fiends and monstrosities and the domain of the alien daelkyr. Some cults of the Dragon d'En-dessous believe that paradise awaits them in the Vallée du Soleil Intérieur, but such cultists also consider gibbering mouthers and Flagelleur mental to be creatures of beauty. Wondrous treasures might wait in the worlds below amid hordes of Démon and aberrations. KHYBER'S INFLUENCE I N KHORVAIRE I n Khorvaire, you might … Find a way to close a passage to Khyber before a horde of horrors emerges from it. • Battle a mind flayer that has established a cult in the sewers. • Stop the spread of a deadly drug or strangel disease flowing from a well tied to Khyber. Khyber is an ever-present threat. Any deep passage could connect to a realm of fiends or spew out an army of aberrations. Despite the magnitude of this threat, portals to Khyber are very rare, and they are stable once found. If you dig a hole in the ground, the odds that you'll eventually reach La Vallée du Soleil Intérieur are infinitesimal. And if a portal to Khyber existed in the sewers of Beaurefuge, odds are good that it would already have been discovered. The risk arises when you're exploring passages where no one has gone before. The sewers of Beaurefuge might be safe today, but if an earthquake opens a new shaft or a group of cultists digs deeper, a previously unknown passage to Khyber could be uncovered. Wherever a passage to Khyber appears, monsters and dark powers can rise up to threaten the world above. Cultes du Dragon d'En-Dessous often have ties to Khyber. Some serve aberrations or fight alongside dolgrims and dolgaunts (see chapter 6). Others can unintentionally threaten a community by releasing something from the underworld: an unnatural disease, a malevolent demon, or a strangel and addictive drug. In dealing with such a cult, the question is not only how to stop their current machinations, but how to seal the passage or prevent it from posing an ongoing threat. Treasures from Khyber can take many forms. The daelkyr create living tools, including Symbiotes (see chapter 5), but any magic item could be presented as an organic creation: a living cloak of the mountebank that teleports its wearer through the plane of madness; a dagger of venom made from chitin and muscle, similar to a scorpion's barb; a crystal ball made by the daelkyr Belashyrra that looks like a Géant eye, casting visions of distant places directly into the wielder's mind. Items recovered from fiendish demiplanes might be constructed from standard materials but have a sinister aspect or appearance, such as a sword of life stealing from the Abyssal Forest of Khar made of jagged, blackened steel. Ombres trail the blade, and it issues a hungry moan any time it draws blood.

Khyber: The Worlds within the World Adventurers don’t have to go beyond Eberron to find strange and magical realms. A layer of stone and soil lies beneath the surface of Eberron, and those who delve below may find natural caverns, subterranean ruins of Dhakaani goblinoids, or the realm of the dwarves of Sol Udar. But there’s more to Khyber than rock and mud. The underdark contains countless demiplanes—pockets of space where the rules that govern the Material Plane don’t apply. These are the source of Khyber’s most unnatural aspects, where its fiends are formed and where the daelkyr remain imprisoned in their own layers (similar to the layers of Eberron’s other planes). Demiplanes can be deadly, but they can also provide an unexpected opportunity for exploration and the discovery of wondrous new worlds just below the surface. The Royaume d'En Dessous section of chapter 4 provides ideas of what it can be like to explore the upper regions of Khyber; this section gives an overview of the demiplanes adventurers might encounter as they delve deeper. What Are Demiplanes? The demiplanes of Khyber are somewhat like the layers of other planes. Each demiplane has limited space, though it could be as small as a house or as large as a nation. Its borders might be defined by impassible physical barriers or walls of force, or the pocket of space could wrap around—if you walk far enough in one direction, you’ll find you’ve looped back to where you began. Reaching a demiplane requires a portal. In some cases, travel also requires rituals or planar conjunctions, and some portals may be impassable, sealed by the ancient wards of dragons or Gatekeeper druids. However, many portals are not only active, but nearly imperceptible; adventurers walking down a tunnel may pass through a portal to the Ironlands without ever knowing it. Portals are static, remaining in one place, and as long as one remains open, adventurers can always retrace their steps to return to it. Demiplanes may have two or more portals, each leading to anywhere on the Material Plane. The realm of Dyrrn the Corruptor has portals beneath the Shadow Marches and the Ironroot Mountains, while both the Kech Shaarat goblinoids of Darguun and the Ghaash’kala orcs of the Demon Wastes make use of portals tied to the Ironlands. As such, demiplanes can allow rapid travel across long distances; adventurers could enter a demiplane below Q’barra, walk what seems like only a mile, then emerge from a tunnel into Breland. Demiplanes have much in common with Eberron’s thirteen planes. Natural laws may not apply within, and time, space, or other elements may behave in unnatural ways. A demiplane could have some of the properties of another plane, like the Burning Bright property of Fernia or the Primordial Matter property of Lamannia. But there’s no universal theme that unites all demiplanes; each one is entirely unique. Some sages say that these demiplanes are Khyber’s dreams. Others believe that demiplanes are unfinished ideas—early drafts of reality or seeds that never quite became planes. While demiplanes are usually limited in size, there’s no inherent logic to their construction. It’s possible to be a mile below the surface of Eberron when you discover a valley that appears to be open to the sky . . . but it’s not the sky of Eberron! Unlike the planes, the demiplanes of Khyber don’t contain any of Eberron’s celestial objects—there could be moons, rings, even suns in the sky, but they’ll be entirely unfamiliar. While there’s no common theme that unites all demiplanes, there are three common categories of demiplane: hearts, prisons, and shadows. Heart Demiplanes The overlords —Rak Tulkhesh, Sul Khatesh, and others—are said to be Khyber’s first children. They were the first fiends to physically manifest, and each overlord brought forth a host of lesser fiends. When a fiend dies, its essence returns to Khyber. Each one is bound to and reincarnated in a particular demiplane within Khyber—the heart of an overlord. This is one reason the overlords can’t be permanently destroyed; each is part of the architecture of Khyber itself, and the overlord’s form that can be encountered in Eberron is simply a projection of its essence. To defeat the overlords, the champions of the Age of Demons used the Silver Flame to bind their immortal essence, preventing them from returning to their heart demiplane to reform. This essentially severed the brain from the heart—but the heart demiplanes still exist. The lesser servants of the overlord—its rakshasa and other fiend minions—return to the heart when they reform, and should an overlord’s bonds be broken, it will recover its full strength in its heart realm. Heart demiplanes are relatively small, around the size of a large city. Each reflects the overlord it’s tied to in appearance and properties. Just as the shard-prison of an overlord’s spirit can affect a region, portals to a heart realm often affect the surrounding area; what’s believed to be a manifest zone to Shavarath might instead be a portal to the Bitter Shield. While the overlords aren’t consciously present in their hearts, their essences still permeate them. Heart realms are typically inhabited by a host of lesser fiends bound to that overlord. Many have no desire to return to Eberron until their overlords are free, while others serve in the Lords of Dust, using the heart as a refuge. A few hearts are described below, but there are at least thirty—one for each overlord. The Bitter Shield: Rak Tulkhesh Rak Tulkhesh’s heart is a crimson fortress, with stones soaked in blood and walls studded with rusted iron spikes. Around the tower’s base, rakshasas and other fiends endlessly battle, their pointless struggle reflecting the bloodlust of their master.

Mordakhesh the Shadowsword often returns to the Bitter Shield between schemes, and is hailed as lord of the fortress. The Bitter Shield has the Unquenchable Fury and Bloodletting properties of Shavarath. The Tower of Shadows: Sul Khatesh The heart of Sul Khatesh is a tower built from black stone traced with silver. It glitters in the light of three unfamiliar crescent moons. Here, it’s always night, and the servants of the Keeper of Secrets sing paeans to the moons as they perform bloody sacrifices and trace eldritch symbols in the soil. The tower holds a library of dark secrets, and beside it, a scriptorium where fiends scribe the books of shadows that may be given to mortal warlocks. Beneath the city of Ashtakala in the Demon Wastes lies a portal to the Tower of Shadows, and the rakshasa Hektula dwells here when she’s not tending to the library of Ashtakala. The Tower of Shadows has the Universal Understanding property of Syrania and the Eternal Shadows property of Mabar. Prison Demiplanes When something is described as being “trapped in Khyber,” it usually means it’s trapped in a demiplane somewhere in Khyber. The most infamous prisoners of Khyber are the daelkyr, but there may well be others—either immortal spirits or mortal creatures that were trapped in the demiplane by their enemies. Dyrrn the Corruptor dwells in the Palace of Sinew, and Belashyrra in the Citadel of Lidless Eyes (both are described in Eberron: Rising From The Last War). Valaara is bound in the Deepest Hive, described in chapter 8 of this book. It’s said that the daelkyr Orlassk dwells in a fortress carved into a giant gargoyle that roams the tunnels of Khyber; it could be that the gargoyle exists in Orlassk’s prison realm, or perhaps the massive creature contains a portal to its prison. When dealing with a prison demiplane, the DM will have to decide the limitations of the portals. In the case of the daelkyr demiplanes, the daelkyr can’t leave them, but other creatures can freely enter or depart. So Dyrrn’s minions can swarm out of the Palace of Sinew, but as long as the Gatekeepers’ seals remain intact, Dyrrn itself cannot leave. The nature of the binding and the power of the daelkyr is such that they have shaped their demiplanes in their image, but lesser creatures could be trapped in more traditional prisons. Shadow Demiplanes Unlike heart and prison demiplanes, shadow demiplanes serve no clear purpose. They aren’t prisons or fortresses of evil, but rather, strange reflections of the world. Much like Xoriat, they often defy natural logic—and this often gives them great value. Beneath the Ironroot Mountains in the Royaume d'En Dessous, the dwarves found a realm where precious stones grow on trees. In the Vale of the Inner Sun, creatures don’t age. Many sages call these “shadow demiplanes” because many seem to be shadows of other planes; the Abyssal Forest of Khaar is a reflection of Lamannia, while the Ironlands bears some resemblance to Shavarath. But in fact, demiplanes of Khyber have no ties to the other planes, nor are they touched by the natural influence of Eberron or the celestial light of Siberys. Perhaps the concepts woven into these demiplanes are echoes of Khyber’s dreams or hints of what might have been . . . or perhaps their resemblance is inexplicable coincidence. Shadow realms may hold important resources that can be used or harvested—but these regions always have a malevolent aspect. Fiends are common, and even mortal creatures that dwell there are sinister. Remaining in a shadow realm for too long is usually an invitation to corruption. There are countless shadow demiplanes, some small and others vast; those mentioned here are just a few examples. The Abyssal Forest of Khaa r At first glance, this seems a primeval forest, but on closer inspection, it’s filled with horrors. The demiplane is tangled in crimson vines filled with blood. It teems with monstrosities, twisted beasts that aren’t as alien as the aberrations of the daelkyr, but just as deadly; even its most charming songbirds are carnivorous and cruel. The forest’s strange vegetation can be used to make potions or deadly poisons, valuable resources—for those willing to brave its horrors. While in the Abyssal Forest of Khaar, any creature that’s not naturally immune to poison damage becomes vulnerable to poison damage, and it has disadvantage on saving throws against poison. The Ironlands This realm’s entire landscape is formed from metal. Adamantine trees grow razor-sharp leaves, and iron blades of grass cut through soft shoes. This demiplane, which has Shavarath’s Bloodletting property, is home to bands of devils and demons that engage in their own endless wars. These fiends enjoy fighting and oppressing mortals, but fortunately, they can’t leave their realm. The Ghaash’kala orcs of the Demon Wastes raid the Ironlands, pillaging weapons from the warrior fiends. The Kech Shaarat (see chapter 4) have expanded their deep vault into the Ironlands; over many centuries, these dar have established an alliance with one of the devil clans, allowing them to hold onto this territory. It’s up to the DM to decide on the foundation of this alliance and whether the Shaarat can leverage it in other ways. The Vale of the Inner Sun A widespread cult of the Dragon Below believes that there is a paradise within Khyber, a place free from suffering and death. The Vale of the Inner Sun does exist, and it has the Stillness of Flesh property of Risia and the Light of Life property of Irian. However, there is a price to this immortality; creatures who dwell in the Vale for an extended time become slowly mutated, eventually turning into unique aberrations. The inhabitants of the Vale—some of whom have been there for centuries—have no love of outsiders, and visitors must prove their worth to bathe in the prismatic light of the Inner Sun.

House Orien and Demiplanes Demiplanes can serve as wormholes to distant locations— a valuable means of transporting people and goods! Orien has discovered one such passage; its enclaves in the cities of Passage (in Aundair) and Varna (in the Eldeen Reaches) are built above portals that connect to a tiny, safe shadow demiplane. This allows Orien to move between these two cities within minutes. However, the two cities are already close and well connected, so this has remained a secret resource instead of being put to widespread commercial use. Recently, however, the war and the Mourning have disrupted many of Orien’s trade routes, and the development of the airship is threatening the house’s dominance of overland travel. Desperate to regain security, Baron Kwanti d’Orien is actively searching for new demiplane channels. He dreams of finding a route providing safe, swift passage across the Mournland, which could become an Orien commercial route or even carry a lightning rail. But Kwanti has no idea just how dangerous demiplanes can be, and in these efforts, he could easily open doors that should’ve been left closed.