Khyber, the Dragon Below, is 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 long past. Still, for those who brave its depths, great rewards await.
Khyber both refers to the physical, subterranean areas of the Material Plane, but also acts as another "layer" to the lane, possessing supernatural properties that can bend space and even time. Two places that are thousands of miles apart on the surface may only be a few miles apart in Khyber.
In Khyber, you could …
The common 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 demons 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 dangerous, but they’re exactly what you expect to find in an underground realm. Such passages might be home to carrion crawlers, giant 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 labyrinth inhabited by demons 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 Mror Holds demonstrate this mystery. Over the past century, the dwarves discovered a vast subterranean kingdom within the Ironroot Mountains. 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 dwarves dug deeper, they opened passages into the unnatural realms and unleashed the hordes of the daelkyr Dyrrn the Corruptor. Passages to Dyrrn’s realm also exist in the Shadow Marches, 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 Silver Flame: 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 strangeness 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 Below believe that paradise awaits them in the Vale of the Inner Sun, but such cultists also consider gibbering mouthers and mind flayers to be creatures of beauty. Wondrous treasures might wait in the worlds below amid hordes of demons and aberrations.
Mindshredder larvae, warriors, and zenthals prey on human oid communities in the caverns of Khyber. If a mind shredder lair lies close enough to the surface, mindshredder warriors (accompanied by a zenthal) will occasionally venture above ground in search of prey, saving enough of what they find for the hungry mindshredder larvae left behind.
In the time before time, the great progenitor dragons turned upon one another. Khyber struck down his brother Siberys and was opposed by Eberron in turn. But the Dragon Between could not, or would not, kill her only living sibling. She wrapped Khyber in her unbreakable coils and transformed herself into a cage of stone and metal, grass and water. She became the world, holding Khyber forever trapped within.
Only a myth? Probably. But if so, it’s a perfectly understandable one. The folk of Eberron can hardly be blamed for seeking some explanation, any explanation, for the alien world beneath their feet.
And make no mistake, it is an entire world. Khyber is larger than the lands of Eberron, stretching beneath the ocean floors as thoroughly as it winds beneath the continents above. Thousands upon thousands of miles stretch and wind and bulge through the heart of Eberron, and every person on all the continents, working together, couldn’t map its reaches.
It’s an alien world. Tunnels wind in impossible patterns, their seeming randomness hiding maddened designs invisible to a sane mind. Great caverns of stalagmites serve as the grazing fields of basilisks and gorgon herds. Chasms large enough to encompass mountains are home to forgotten cities of grimlocks, mad dwarves, or other, older races never seen by surface dwellers. Carved, or sometimes grown, from the rock, these cities spread across the massive hollows. Their citizens subsist on fields of fungi grown taller than wheat, and think thoughts never illuminated by the light of the sun. Yet they are thriving communities, ready to trade with visitors—at least until those visitors do or say something wrong and find themselves sacrificed to powers of the eternal dark.
Rivers sink to depths unimagined, feeeding vast seas black as darkest night. Islands, some tiny, some the size of small continents, lurk within those darkened waters, and even the eldest dragon sages don’t know what dwells upon them.
Far beneath the earth, farther than most mortals dare to dream of descending, imprisoned horrors of past epochs bide their time, waiting for the day their shackles fail. Overlords remain where they were thrown down in the Age of Demons. Some are mere essence, imprisoned within Khyber dragonshards; others still retain their bodies, held within cells of arcane device. Remnants from the time of the Xoriat incursion, when madness walked the surface of Eberron clad in mortal flesh, the daelkyr and their minions still stalk the tunnels below. They too are imprisoned, prevented from returning to the surface, but in Khyber their steps are unhindered, and they carve out kingdoms of their own. Aboleths lurk in pools of foul fluid and dream of enslaving the minds of mortals. Mind flayers, the first harbingers of the daelkyr, oversee cities of humanoid slaves and hatch their plans to extend the borders of Khyber until all of Eberron is a sunless, blasted land of madness.
Near the prisons of the overlords, within the dominions of the daelkyr, and in the almost infinitely deep reaches of Khyber’s passages, the world warps and shifts into something other. Khyber is not Eberron, and the laws of Eberron hold no sway in the depths. Colors never seen by human eyes glow from crystals unlike any dragonshard and press ominously against the mind. Rivers of liquid stone flow through passages that follow no rules of physics or geometry. Tunnels open into a darkness so thick that it has weight, scent, taste, and life. Some say that these passages lead to Dolurrh or Mabar. Others claim that the deepest reaches of Khyber drop away into Fernia, Risia, and the other depths of the Elemental Chaos, including the cancerous Abyss eating away at its heart. These aren’t manifest zones, but true walkways into other worlds where Khyber eats away at his prison. And if no people alive today can confirm these legends, well, neither can any say that they are false.
This is Khyber: passage and prison, city and sea, bridge and barrier, darkness and death.
There’s no reason a “standard” adventure such as a dungeon crawl or a quick trading expedition can’t happen in the passages of Khyber, just as it can in any mundane complex of tunnels. Doing so isn’t “wrong.” On the other hand, Khyber can provide unique locations and encounters for players, and a Khyber-based adventure is the perfect opportunity to vary the feel of a campaign. Here are some suggestions for making Khyber-based adventures stand out.
Alternate Cultures: Khyber-based adventures are perfect opportunities to introduce alien cultures. Try presenting humanoids not normally seen on the surface, such as kuo-toas or grimlocks, or just play with cultural mores. Want to have a city that combines the sacrificial traditions and priestly castes of the Aztecs with the psionic “thought police” from the most nightmarish cities of Sarlona and can’t think of a place for it in Eberron? An enormous cavern in Khyber might be just the place.
Attrition: Many D&D campaigns don’t track details such as food or ammunition; for many people, such bookkeeping violates the aesthetic of high adventure. But a prolonged series of adventures in Khyber presents the perfect opportunity to experience a grittier existence. The PCs don’t have an easy means of retreat and resupply. Suddenly, scavenging for food becomes important, and a scarcity of arrows might force more close-quarters combat, or more frequent retreat. It might even prove difficult to find a safe place to rest, forcing the party to face more than a day’s worth of encounters at a stretch. Don’t put the players through this situation too often, because it can become frustrating for them, but a few days of careful planning and hoarding provides a different feel to a game.
Historical Importance: Khyber contains places and creatures of great historical importance. PCs who enter its depths could have to deal with creatures that devastated the world in the ancient past, uncover lost relics, or learn the fate of past explorers. The chance to interact with the greatest villains of history might be a more memorable reward than any treasure.
Impossible Environments: Some regions of Khyber—particularly those near the prisons of overlords, the center of a daelkyr lord’s domain, or the borders of other planes—don’t follow natural laws. Want to play out a chase or a running battle through a series of caves where a given archway doesn’t necessarily take you to the same room twice? How about an encounter on a bridge of solid flame above a river of rushing stone, or on a series of ledges at different angles, resembling an M.C. Escher painting? Or a battle with a horde of undead that continue to rise when they’re slain, until the energy emanating from a particular dragonshard is contained? Khyber is the place.
New Game Features: Want to introduce a new mechanic to your campaign? Maybe a new monster, a new class, or an old classic you’ve never used before? It’s possible to do so on Eberron’s surface, but if you don’t think such a feature fits the mood you’ve established above, consider using the lost cities and isolated islands described below.
Wild Mechanics: Khyber is a great excuse to just go wild. Have in mind a trap of otherworldly tendrils slowly drawing its victims through the surface of an otherwise solid wall? Or a chamber in which light is dark and dark is light? How about having the PCs face a gorgon whose breath petrifies them, yet somehow they remain animate and must find a means of restoring themselves as they slowly grow more resilient but also less mobile? Such options are possible in the peculiar depths of Khyber.
Entrances to Khyber can be present anywhere. Natural crevices might descend far enough to open up within the confines of the Dragon Below. Ancient dungeons and ruins might contain winding stairs that seem to descend indefinitely, or magic portals that transport hapless travelers farther down than they ever wanted to go. Western Khorvaire, which was the center of the greatest battles with the daelkyr, has the largest number of these entrances, some of which were found and sealed by the Gatekeepers.
Cazhaak Draal: This ancient hobgoblin city in Droaam, now ruled by a tribe of medusas, sits atop a shaft leading into Khyber’s upper reaches. Goradra Gap: The Goradra Gap is a vast chasm in the mountains of the Mror Holds that is over a hundred miles in length and deeper than any instrument can measure. Those who would use this passage as an entry to Khyber must first win past the beast said to dwell within, reportedly larger than even the mightiest dragon.
Lair of the Keeper: Located in the northern reaches of the Demon Wastes, this is the abode of a great dragon—possibly undead—believed by some to be a manifestation of the deity known as the Keeper, one of the Dark Six (see page 244). In the depths of his lair, he keeps dragon shards filled with the souls of the lost. Adventurers who delve deeper than that find themselves beneath the skin of Eberron.
Pyramid of Ebon Flame: One of the scattered creations of the giant wizard-king Addis-Ro, the Pyramid of Ebon Flame is a surviving ruin of Xen’drik’s ancient empires. Although primarily a necromancer, Addis-Ro was said to have experimented with powers drawn directly from the depths of Khyber, and this huge, unbreakable, black glass monolith supposedly marks the passage through which he made his journeys below.
Sharn: This most famous city reaches for the heavens, but its roots are planted firmly in hell. Through the deepest of its tunnels, sealed since the War of the Mark, intrepid or foolhardy explorers might find paths into Khyber.
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 Realm Below 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.
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.
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.
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 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.
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.
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 Realm Below, 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.
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.
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.
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
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.
In Khorvaire, you might …
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 the Vale of the Inner Sun are infinitesimal. And if a portal to Khyber existed in the sewers of Fairhaven, 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 Fairhaven 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.
Cults of the Dragon Below often have ties to Khyber. Some serve aberrations or fight alongside dolgrims and dolgaunts. Others can unintentionally threaten a community by releasing something from the underworld: an unnatural disease, a malevolent demon, or a strange 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 symbionts, 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 giant 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. Shadows trail the blade, and it issues a hungry moan any time it draws blood.
| d10 | Trinket |
|---|---|
| 1 | A pressed flower with vivid green petals; when you smell it, you hear eerie music |
| 2 | A tiny ball of putty; if you set it down, it begins to slowly crawl around |
| 3 | A perpetually warm disk of dark iron |
| 4 | A small journal with leathery pages; any words you write in it slowly disappear |
| 5 | A four-sided die carved with strange markings |
| 6 | A cameo with the silhouette of an unknown species |
| 7 | A preserved finger with purple flesh and four joints |
| 8 | A perfectly preserved eye; if you set it down, it rotates to follow your movement |
| 9 | A small box; when opened, you alone hear screaming |
| 10 | A preserved insect; you’ve never seen another like it |