"If it does not rot, if it can lie like this here forever...is it truly dead?"
- — Savant Preem
The Yu'vath were an ancient and corrupted alien-empire that inhabited the Calyx Expanse two standard millennia ago, during the Angevin Crusade. These evil xenos were no more than twisted servants of the Warp who built an empire on a foundation of dark sorcery, soul-slavery and daemon worship. For years the Angevin Crusade fought a bloody war against them, slowly pushing them back in the face of massed slave armies and vile Warp-technology. Finally Saint Drusus himself struck the final blow and ended their domination over the Calyx Expanse. What was left of their worlds and artefacts were destroyed and their locations purged from the Imperial records. Over time their existence was slowly forgotten. Whispers in the Koronus Expanse persist, however, that they were never truly defeated and there are inhabited Yu'vath worlds still hidden deep within the darkness of the Calixis Sector.
A great evil once moved across the Koronus Expanse in a past age, a dark power that murdered the very stars, cluster by cluster. Dead xenos worlds orbit these stellar remnants, blasted molten in ancient death throes and then frozen beneath the wan light of a star-ember. Their ruins are cyclopean, their under-crust warrens labyrinthine, and their dire symbols, where not worn to dust by the passage of aeons, warn of xenos sorcery and ancient doom; they speak of the Yu'vath. The Yu’vath were a blight upon the Calyx Expanse in the era of Lord-Militant Angevin, prior to the creation of the Calixis Sector in the fourth century of the 39th Millennium. The Warp-worshipping Yu'vath enslaved worlds though vile xenos sorcery, expending the lives and souls of corrupted human slaves to build such horrors upon the Calyx Hell Worlds that chroniclers of the Angevin Crusade forbore to record them. The Warp-ridden Yu'vath and their tormented slave armies bled the Crusade's forces for decades before their ultimate extinction at the hands of General (later Saint) Drusus and the Adeptus Astartes. Even now, chronicles of the Angevin Crusade's victories over the Yu'vath are restricted works, and few Imperial savants know what came before the blessed establishment of the Calixis Sector.
- Dark Energy Constructs - Of great danger to the Imperium are the Yu'vath Dark-Energy Constructs. These are the forgotten weapons of the ancient war that raged across the Koronus Expanse during the time of Saint Drusus and the Angevin Crusade. Of these, the Whisperer (see below) is the most powerful, an alien battleship shaped from Warp energy and dark technology. However, there are others scattered across the system. These include the Dark Lament; a complex Warp energy web that the Yu'vath would lay over ground or structures to turn the very environment against their attackers and the Void Wasps; Yu'vath interceptors.
- The Resonance - The Resonance is Yu'vath machinery, though it is much more Warp-sorcery than mechanism. On the world of Scintilla lie the xenos ruins of Designate-228-18. Though Imperial archeotechs have guessed that the structure is xenos in nature, if the truth of its construction were known, it would portend dire consequences. The vaults of Designate-228-18 were constructed by the Yu’vath, a Warp-worshipping xenos breed whose empire of corrupted human worlds bled the Angevin Crusade for decades. Complexes like these were used to create Hell Worlds--swirling centers of Warp-tides, sustained by foundation-tunnels of human sacrifice and machine-enhanced psyker agony. The Resonance suffuses the rock of lower levels of Scintilla, dormant and invisible to commonplace Imperial technology. In the depths, the Resonance works a slow, insidious effect upon human minds, for in ancient days the Yu'vath corrupted their human slaves by forcing actions that fragile minds then justified as their own choices. Residents deep within Scintilla's hive cities often begin to suffer hallucinations, false memories, and waking dreams as their minds rationalise what is happening to them. At each stage, the person hallucinates or constructs false memories to explain his actions: orders from superiors; accompanying comrades; that he is following or fleeing something. As the actions become more bizarre, so to do the hallucinations. Talking to others can break the Resonance's immediate hold by showing the afflicted that he is in the grip of hallucination -- but he still will not know that his actions were forced upon him.
- Crown of Wonders - These crowns set upon ancient mummies are circlets of black, flexible material, steeped with psy-power and ornamented with curling projections on the outer surface. They are a Radical Inquisitor's prize--and curse, as they slowly twist a psyker's mind. Wonders of the Yu'vath bubble up within the mind: wise, angelic beings that guide humanity to rightful adulation of the Ruinous Powers and joyous depravity. The lies begin as a whisper, then grow to a blasphemous torment. Soon, the psyker cannot distinguish the visions from his own beliefs.
- Shard Spiders - Another construct of the Yu'vath, these deadly little creatures are fashioned from bruised purple crystal and are about the size of a large dog. With twelve legs and a tiny central body they scuttle about with alarming speed. They also have a set of needle-like mandibles which they can alternatively use to mend broken crystal or plunge into an unwary human's soft flesh.
- The Whisperer - In the aftermath of the Angevin Crusade's bloody war with the Yu'vath, the remnants of these xenos' slave armies and techno-Warp constructs were scattered, broken and dying, across the Koronus Expanse. For the most part, these grim reminders of the alien's dark empire slunk away into the shadowy corners of the void, and were lost from sight forever. However, some were found by those who came after--explorers, treasure hunters and Rogue Traders. The Whisperer, an ancient, sentient Yu'vath voidcraft constructed of dark energy, is one such spoil--discovered in a forgotten battlefield between unnamed stars by a Rogue Trader of an unknown dynasty. Unable to return with it to the Calixis Sector (where Imperial powers would have been sure to destroy it), but also believing it too valuable to abandon, the Rogue Trader took it to the newly-founded Svard System and concealed it beneath the rolling cloud layers of the system's gas giant. Here it remained, considered harmless, until such time as a descendant of the original Rogue Trader could return and learn its secrets. Unfortunately, he never did and was lost to the void like so many before him—and so the Whisperer was forgotten. Early in the ninth century of the 41st Millennium, a strange phenomena began to appear among the citizens of the dying Svard System. People were having dreams of a great dark presence--always close by but always unseen--that would whisper into their ear as they slept. No one could remember what this presence was or what it had whispered to them, but the fact that it was afflicting so many people, of all castes, ages and locations, prompted the star system's governing body--the Crystal Council--to begin an investigation based on fears of Warp-sorcery or the emergence of a proscribed cult. Unfortunately, before any real knowledge as to the nature of the dreams was uncovered, the entire system began to suffer acts of terrorism and sabotage. Ordinary citizens began attacking their neighbours and striking at the very infrastructure of the system itself. At first, the council thought this was its fears of a cult confirmed, but as reports flooded in, they could find no plan behind the attacks beyond anarchy and no link between the attackers beyond the fact that most seemed to have dreamed of the Whisperer. Soon there were countless scores of Whisperers -- ordinary citizens turned by the subversive power of the Yu'vath vessel that was trapped within the gas giant of the Svard System. These Whisperers had become "cannon fodder" for their xenos master and soon existed in the hundreds of thousands. Whisperers are, in essence, citizens of Svard turned to the will of the original Whisperer. Whisperers are not zombies or automatons, but rather living, breathing, thinking humans that will work together as a well-trained team under the guidance of the Whisperer. They are also very creepy to talk to or even to be near when their true nature is known, for while they can counterfeit emotions and even show fear, they have (in a way) had their souls scooped out and show no humanity or reluctance in the face of the terrifying and the amoral. Whisperers are also not religious fanatics--in fact, they do not worship the Whisperer, or even acknowledge its existence since they just do not think about such things. They are just extensions of the alien construct's will; clever semi-autonomous extensions that can draw on their past skills and memories, but extensions nevertheless. If the agents of the Imperium can manage to find and destroy the Whisperer, those turned by his dark dreams will recover -- although they may never be trusted by their fellow citizens again. The motivation of the Whisperers is simple; fulfill the will of the Whisperer. In essence, they are its puppets and enact its will within the Svard System. The motivation of the Whisperer is to repair its wounds and free itself from the gravity well of the gas giant, thus destroying the Svard System, and then to escape into the void to complete its ancient mission of war against the Imperium. To this end, it has spent years dominating the weakest human minds of Svard and using them to supply it with fabricated materials and massive amounts of raw energy. Needless to say, should the Whisperer manage to escape, it would wreak havoc across the Koronus Expanse and the Calixis Sector.
- Yu'vath Bone Warden - An ancient Dark-Energy Construct, the Bone Warden is a fell union of Warp-based technology and dark sorcery. They were crafted by the Yu'vath primarily to act as watchmen and guardians for their void crypts and solar fortresses; and even now, long after their masters have been forgotten, they remain to fulfil their duty. The Bone Warden has no physical form and instead resides in a collective of dead matter--most often corpses or other once-living remains. These corpses are held together by ribbons and arcs of crackling black energy, the air around them charged with constant flashes of midnight electricity and the smell of burning flesh. Acting as a single mass, the corpses form a cloud of grasping, clawing hands and mouths that whirls through the air. The only way to defeat a warden is to destroy its physical state and thus disperse its dark energy field. However, even as its adversaries blast away its fleshy shell, it uses its warp-shard crown--a collection of dark crystalline fragments that orbit its energised core--to claim more physical matter, regenerating its rotting form. For this reason, Bone Wardens are often found in rooms well stocked with the dead -- a ready made supply of material left by their Yu’vath masters.
The incomprehensible construction of the voidships of the Yu'vath do not seem to require the same components that more mundane vessels do. These vessels have no actual crew population.
An ancient device of the Yu'vath, the Whisperer was created from dark Warp magics and cold alien technology. Easily a match for most Imperial ships of the line, it also has the power to subvert minds and bend the weak-willed to his cause. In appearance, it is a massive ball of dark, reflective energy several kilometres across. Around it orbits a collection of monolithic rounded crystals, power constantly arcing between them.
- Hull: Unknown
- Class: Unknown
- Dimensions: approx 3 kilometres in diameter, crystal orbit out to 6 kilometres
- Crew: Unknown
- Mass: Unknown
- Acceleration: Unknown
The following are some of the few identifiable components for Yu'vath starships. Yu'vath voidship components are not powered in ways humans could understand, and do not have space or power requirements. They also cannot be incorporated into human vessels:
- Yu'vath Gravity Sails - Gravity sails can touch the forces that bind stellar systems together, allowing their ship to move with agility and grace.
- Immaterium Energy-Arc - Far worse than the Rupture Cannons, these energy-arcs seem to be generated from the cores of Yu-vath vessels, and no armour can withstand them.
- Void-Skein Rupture Cannon - A strange and terrible abomination of a Macrobattery, little is known about these xenos weapons. They seem to fire munitions through the Warp, with the warheads only emerging into realspace just before they strike their target.
- Dark Heresy: The Radical's Handbook, pg. 211
- Rogue Trader Core Rulebook (RPG), pgs. 359-360
- Rogue Trader: Dark Frontier (RPG), pg. 6
- Rogue Trader: The Game Master's Kit (RPG), pp. 10-11, 17, 19, 27
- Rogue Trader: The Koronus Bestiary (RPG), pp. 102-114
- Dark Heresy: Apocrypha - Dark Heresy Timeline, pg. 4