This article concerns the Grey Knights' homeworld; for the Adeptus Mechanicus' massive combat walkers see Titan.
Titan is the largest moon of the gas giant Saturn in the Sol System and is wholly controlled by the Grey Knights Chapter of psychically-active Space Marines who serve as the Chamber Militant of the Inquisition's Ordo Malleus. The fortress-monastery of the Grey Knights is based on Titan, and is carved entirely of basalt. Within the fortress hang pennants, banners and flags commemorating the victories and sacrifices made by the Chapter in their eternal war against the daemons of Chaos, but none other than the Grey Knights would recognise the names of these campaigns. This is because the Chapter operates in oppressive secrecy, beyond the knowledge of the Adeptus Terra and even often of the Imperium of Man's ruling High Lords of Terra. As a part of the Ordo Malleus, the Grey Knights are answerable only to the Inquisitor Lords of that division of the Inquisition and the Emperor of Mankind Himself. Even the location of the Grey Knights' fortress-monastery on Titan is known only to the Ordo Malleus and its agents. Titan itself is surrounded by the rings of Saturn and the other moons of the gas giant which are all highly-secret Inquisition-controlled worlds, including: Mimas, the prison and execution centre of the Ordo Malleus, Enceladus, the home of the most powerful Inquisitor Lords of the Ordo Malleus and other influential Inquisitors of that Ordo, and several other satellite worlds all dedicated to the highly secret Imperial task of confronting the corruption of Chaos across the galaxy.
The Grey Knights Space Marine Chapter is the most mysterious of all the Imperium's myriad organisations. Few outside the upper echelons of the Inquisition hold any knowledge of the Chapter's Founding, and even these most trusted of men and women are denied the full truth. According to legend, the Grey Knights first appeared during the tumult of the Second Founding in the early 31st Millennium after the Horus Heresy when the nine remaining Loyalist Space Marine Legions were first divided into the present-day organisations known as Chapters. Designated Chapter 666, the Grey Knights were the culmination of a project begun by the Emperor during the final days of the Horus Heresy. When the perfidy of his most favoured son, the Primarch Horus, was revealed following the events of the Istvaan III Atrocity, the Emperor foresaw that the end of the Horus Heresy would cost Him greatly, so much so that He would no longer be able to take an active hand in Mankind's survival -- if He survived at all. The very nature of the Horus Heresy had proven that the Space Marines were not immune to the corruption of Chaos as the Emperor had once hoped. So did the Emperor set His hand to plans that would win a wider victory from the ashes of a most personal defeat. Malcador the Sigillite, the Regent of Terra, a man who had served at the right hand of the Emperor for as long as anybody could remember, had been gathering to him men and women with particular talents since the end of the Great Crusade. At first working for him in an informal, secretive and ad hoc capacity, with the enemy at the gates of the Imperial Palace he shared his vision with the Emperor and brought before Him twelve beings of unswerving virtue who he had recruited on his master's behalf.
By the time Malcador returned to his Emperor with these chosen men and women, Terra itself was under siege by Horus' Traitor Legions, and only through the most artful of subterfuge were the Sigillite and his recruits able to pass unscathed through the battlelines and come unharmed and unseen before the Emperor. Malcador initially chose 12 persons of "an inquisitive nature" -- four of those would become the founders of the Inquisition but the other eight, all Space Marines of differing Legions and unparalleled psykers in their own right, would become the eight founding members of the Grey Knights -- the first Grand Masters of the Chapter. In stern silence the Emperor surveyed the robed figures that Malcador had brought before Him, and He saw that his faithful servant had done well. Of the twelve, four were Imperial lords and administrators possessed of inquisitive nature and unyielding strength of mind. The other eight were Space Marines whose abilities were as peerless as their dedication to the Emperor. Some hailed from Legions that had abandoned the Emperor's light in favour of Horus' dark promises, but these Battle-Brothers had never lost their loyalty and had fought the Heresy from within. Fulsome in his approval of the selection, the Emperor bade Malcador proceed with the next stage of his plan.
So dismissed, Malcador and the twelve departed the embattled palace as unremarked as they had arrived. Yet when the group departed Terra they divided, for their destinies would be separate for a time. The four Imperial lords left to lay the framework of the Inquisition -- that mighty and secretive organisation charged with keeping watch over all arms of the Imperium to prevent both corruption within and attack from without -- while Malcador took the eight Space Marines to the moon of Saturn named Titan. Following the dire events of the Horus Heresy, across the galaxy, forces still loyal to the Arch-Traitor continued to fight the war he had declared, razing planets and claiming dominion over vast tranches of human worlds. The forbidden knowledge shown to Horus that had been the catalyst for his fall from grace bore other more sinister fruit, and dwellers from the other side of reality, the Empyrean, were now abroad in the material realm. Though many at the time of the Heresy believed the word to be childish and loaded with superstition, they came to be called daemons, for lack of a better and more descriptive term in the Gothic language. Whatever name given to them, their existence itself was all too horribly apparent. At points all across the galaxy, the Materium had been worn thin and the veil between realities torn open. The Eye of Terror blinked open, casting its malign gaze on the destruction so freshly wrought as world after world became conduits for the unreal to enter the real.
The Loyalist Legions were diminished, their fighting strength a paltry fraction of its pinnacle and their Primarchs dead or at each other's throats in the power vacuum that followed the Emperor's internment in the arcane mechanisms of the Golden Throne. While the Emperor had foreseen the myriad dangers humanity faced and created the Legions in His own image to combat them, even He could not have anticipated the monstrous forces now unleashed upon the Imperium. While the Legions had been bred to fight wars on the material realm, this new foe could battle on the immaterial front too, rendering Space Marines little more effective than the common mortal soldier when it came to psychic war. Many of the Legions had once welcomed psykers into their ranks but an Imperial edict at the Council of Nikaea barring His sons from utilising the potential of their Warp-gifted troops had been passed in the years before Horus's betrayal and endorsed by the Emperor Himself, eliminating the Librarius from every Legion. Denied the one weapon that could reasonably have altered the course of the opening stages of the interstellar civil war, in time the Primarchs came to see its true power and the Loyalist Legions gladly welcomed Librarians among their number once again. But one man had always known the capability of that weapon and had foreseen a time when humanity would need to fight the powers of the Warp with powers born of the Warp.
Through sorcerous means, the Sigilite had long ago occluded the moon of Titan from the sight and deeds of Loyalists and Traitors alike, covertly building a fortress-monastery and equipping it with forbidden technologies and secret training facilities to prepare the new Chapter in its role defending the Imperium from daemonic incursion. New supplies of gene-seed, newly derived from the genetic material of the Emperor Himself, lay preserved in cryovaults, and fresh-forged armaments stood ready in cloistered armouries. Theirs would not be a full Space Marine Legion, but a Chapter -- a smaller, more tightly knit brotherhood, but one with numbers enough for the task at hand. In addition to the eight founders, thousands of others had been taken to the hidden satellite to serve as ancillaries, Chapter Serfs and the recruits that would from the original Brotherhoods (companies) of the Chapter. Malcador oversaw the initial creation of the Grey Knights, but he could not remain to oversee their evolution, so he selected one of the eight to lead the Chapter in the years to come. So did Janus become the first Supreme Grand Master -- the hand that would guide the Grey Knights through their first challenges. Before leaving Titan for the final time, Malcador forged one last enchantment of arcane technology and psychic accumen, greater than any that had come before it. Titan vanished completely from its orbit, hidden from Horus in the most unlikely of refuges -- Malcador had anchored it amongst the tides of the Warp. Protected by Macro-Geller fields and sigilic rites of Malcador's own devising, Titan rode out the tumult of the Warp whilst the rest of the galaxy endured through the last slar months of the Horus Heresy and the tragedy of the Emperor's final battle.
For centuries the Grey Knights dwelt on Titan while the Sigillite kept them hidden from reality, training their minds and arming themselves with the knowledge they would need to go forth and eradicate the daemonic from the material realm. For hundreds of subjective Terran years the Grey Knights trained and prepared, to not only armour their mind from psychic assault but also to turn it into the sharpest blade with which to sever their enemies' links with the corporeal. But knowledge was the most powerful and the greatest of the weapons that they armed themselves with. For hundreds of years the Grey Knights prepared to do battle with the Neverborn, drawing on the entire libraries at their disposal prepared for them by Malcador that were filled with books that listed the rituals of banishment, the rites of warding and, most importantly of all, the true names of hundreds of daemons.
When the Grey Knights did finally take their place back in the Imperium, less than a standard decade had passed in real time, but for the warriors of Titan many standard centuries had elapsed. Men who were young during the twilight years of the war against Horus were now older than the oldest surviving veterans of the fragmenting Space Marine Legions. Those eight who had previously worn Power Armour of a differing colour had accrued more years than even the most ancient and venerable of Dreadnoughts. Yet, the galaxy was still in turmoil. The surviving Loyalist Primarchs bickered over how best to prevent a rebellion on the scale of Horus’s from ever happening again, while the defeated Traitors preyed upon worlds still loyal to the Golden Throne, as did newly emboldened xenos races. But against this backdrop, the malign influence of the Warp had not dwindled -– if anything, it had intensified –- and the Grey Knights threw themselves straight into the fray. Even at present, in the closing years of the 41st Millennium, the Grey Knights continue their never-ending and secret battle against the Forces of Chaos.
The Citadel of Titan
On Saturn's moon of Titan, nestled at the base of the shadow of Mount Anarch, the fortress-monastery of the Grey Knights, known as the Citadel of Titan, juts from the ice sheets and oceans of liquid methane like a jagged black spire. Built by the Emperor over ten thousand years ago, the Citadel of Titan has endured through countless ages of war and strife. Covered with dust and shadow, the dark edifice is festooned with macro cannons and massive lance turrets, their heavy barrels aimed out into the night. It is a forbidding sight that welcomes no visitors and brooks no trespass. In fact, even the existence of the citadel is a closely guarded secret, and in the populous space lanes of the Sol System vessels give the moon a wide berth, their captains well aware that it does not pay to stray too close to the ominous moon.
Long has this fortress stood. Its dusty, echoing halls are hung with battle honours stretching back almost ten thousand standard years, though few outside the Chapter would recognise the names of the conflicts inscribed in the faded gold lettering. Within the frigid halls of the citadel, servitors and Chapter Serfs shuffle along empty corridors and tend to the millions of menial tasks required to keep the fortress running. Occasionally, a towering Grey Knight will stride past, always with purpose and always cloaked in the menacing air of barely contained power. The citadel is the heart of the Chapter, a place for battle-brothers to rest, meditate and train between their endless battles.
This mighty structure, designed to accommodate over a thousand Space Marines and all their weapons of war, stands largely silent and empty. The daemonic threat can strike anywhere across the galaxy and, in opposing that threat, most of the Grey Knights are scattered throughout the stars at any given time. Only in the Chamber of Trials, where the unceasing work of recruitment and training is carried out, does clamour reign. Elsewhere, the Grey Knights go about their duties in silent meditation, their thoughts bent upon their unending mission.
- Apex Cronus Bastion - This mighty space station, which is the size of a small moon, orbits Titan and is considered one of the most formidable star fortresses in the Imperium. It is rumoured to surpass even the Imperial Fists Chapter's mighty warship Phalanx in firepower.
- Archivum Titanis - This is where the battlefield reports of the actions conducted by the Grey Knights are stored within the shelves of the Archivum.
- Augurium - The silver pinnacle that contains the mirrored chamber known as the Augurium lies at the top of the fortress-monastery's tallest tower. Within its mirrored walls, the Grey Knights' Prognosticars go about their rituals and meditations. In function, the Prognosticators are responsible for tracking the unholy spoor of daemons through the roiling tides of the Immaterium to wherever they emerge or are summoned into Imperial space. Such is the secretive nature of the Grey Knights' duty and so duplicitous are the foes they face that they cannot rely upon other servants of the Emperor to guide them to their prey. In most cases, by the time a planetary governor sends out a panicked astropathic cry for aid and the presence of daemonic forces is both detected and verified, it will be too late. Instead, the Grey Knights rely upon their Prognosticars to alert them to daemonic incursion, often months or years before these events occur, allowing them to appear before aid is called for and close the tears in reality before they can widen and flood realspace with Warp energy –- the lifeblood of the Daemon. Prognosticars are Grey Knights especially gifted in reading the ebb and flow of the Warp. Ensconced in the Silver Pinnacle, the central tower of the Citadel of Titan, this handful of battle-brothers spend their lives untangling the strands of fate and looking into the future of the Chapter. The mirrored chamber of the Prognosticars, known as the Augurium, reflects the thoughts of the Grey Knights back upon themselves. Each battle-brother must then sift through images from the past, present and future, looking for meaning, and the writhing black coils of daemonic entropy that reveal where the veil between worlds will be torn and daemonic forces gather.
- Broadsword Station - The sky above Titan glitters in the dark with dozens of orbital defence platforms, warships and void-fortresses. Among these vast, drifting structures can be found Broadsword Station, berth of the Grey Knights fleet, and launching point for the Chapter's forays into the wider galaxy. Hanging in synchronous orbit above the fortress monastery, the station's huge macro-batteries and torpedo arrays form the Grey Knights' first line of defence against attack. The guns of the station can even be angled to point down onto Titan should the unthinkable ever happen and the citadel fall, or, worse yet, its daemonic prisoners escape their sorcerous containment. At any one time there are dozens of Strike Cruisers gathered around Broadsword Station, undergoing repairs or preparations for missions. The Grey Knights' alliance with the Adeptus Mechanicus, as well as their favoured position alongside the Inquisition, ensures that their vessels are among the finest the Imperium can create, and few ships match them for speed. The station also acts as a training facility for those Chapter serfs and specialist servitors destined to act as crew on the Grey Knights' ancient ships. Unlike the lumbering battleships of the Imperial Navy, with their corridors and bilges packed with press-ganged ratings, the vessels of the Grey Knights boast expert crewmen. The Grey Knights are also blessed with patronage of their own Navigator House of the Navis Nobilite. By millennia-old accords these Navigators guide the Chapter's ships through the Warp, often enshrined on a vessel from birth to death to keep the secrets of where they have gone and what they have seen.
- Chamber of Purity - A deep chamber that lies amongst the roots of Mount Anarch, this is the oldest part of the citadel of the Grey Knights. It is here that the Purifiers, the noblest of the Grey Knights, are quartered, and few outsiders are permitted within. The Purifiers are those Grey Knights whose very being is anathema to Daemons, their psychic presence not just unpalatable to creatures of the Warp but actively harmful. No more than a few dozen in number, the Purifiers maintain the Chambers of Purity, keeping its daemonic relics and restless spirits from stirring to life. It is here that the most twisted trophies of the Grey Knights are locked away, those profane objects too dangerous to study or hang in the Hall of Champions. Books, blades and bones held immobile in gilded stasis caskets fill niches all around the chamber, the ancient technology and the powerful will of the Purifiers keeping the daemonic artefacts dormant. The Iron Grimoire, a sacred tome penned by Malcador and kept safe by the Supreme Grand Master, tells of another reason for the existence of the Chambers of Purity. It hints at a great evil imprisoned under the citadel, something buried there by the Emperor during the unification of the Sol System; something that could not be killed. For this reason the Chambers of Purity must always be guarded by at least one Purifier, lest this evil awaken from its millennia-long slumber.
- Terminus Decree - The Terminus Decree is a set of ancient instructions written upon millennia-old parchment and sealed within a mysterious artefact of the Grey Knights Space Marine Chapter. This artefact goes unrecorded in all the libraries of the Imperium, for it has been kept secret from all but the Supreme Grand Masters of that Chapter. It is said that the Terminus Decree contains the final secret of the Chapter, a secret so great that it could destroy the foundations of the Imperium -- or provide salvation in its darkest hour. Deep within the Chambers of Purity, within the Grey Knights fortress-monastery on Titan, locked away in the chamber said to hold the tomb of Malcador the Sigillite himself, rests a simple wooden box, embellished with a golden seal. Within this box is the ancient parchment that contains the instructions known only as the Terminus Decree. Only a Supreme Grand Master of the Grey Knights knows how to open the box, and he will do so only when all hope for the future of humanity seems lost. The Terminus Decree is the ultimate sanction of the Grey Knights, a secret so vast it could bring the Imperium to its knees, or save it in its darkest hour. The exact nature of the document is unknown, and the only clue to its contents lies in the box's golden seal. It is whispered that it is the exact match of another seal, found only in one place in all the Imperium of Man's many scattered worlds: within the Imperial Palace, upon the Emperor's Golden Throne.
- Chamber of Trials - The Chamber of Trials is a forbidding keep set alongside the main bulk of the citadel where the Grey Knights train their aspirants. It is from the Chamber of Trials that the Gatherers set out across the galaxy in search of new recruits for the Chapter. The Gatherers are Grey Knights whose great age or severe injuries no longer permit them to undertake the primary work of the Chapter, but whose keen senses and minds can still detect an Aspirant hero from amongst the common rabble of humanity. The Chamber of Trials is where Aspirants arrive and their training begins -- if they survive.
- Cloister of Sorrows - The Cloister of Sorrows was a place of contemplation -- open to Titan's sky, its atmosphere contained within invisible electromagnetic fields so that the great eye of the galaxy could look down upon the Grey Knights. The Emperor was a part of that gaze, always examining the soul of every one of His servants.
- Dead Fields - Beneath the Grey Knights' fortress proper lies a cool, damp crypt called the Dead Fields. It is here that every Grey Knight wishes to finally reside, in the hallowed halls of the glorious dead. When a Grey Knight falls in battle, and his body can be recovered, his brothers will carry him back to Titan. His body will then be carefully prepared for burial, his gene-seed removed and his flesh washed of the taint and filth of war. Specially blessed servitors will then paint the 666 words of sanctity upon the body of the dead Space Marine, until he is covered in fine script from head to toe. He will then be encased in his burial armour, a suit of silvered plate mail, and his hands wrapped around a heavy steel sword inscribed with his deeds. His matchless arms and armour –- aegis suit, Nemesis force weapon and storm bolter –- are taken back to the Chapter's armoury for future generations of Grey Knights, though they will always bear his name; tiny spidery scrawl coils around grips and barrels documenting hundreds of names almost invisible to the naked eye. So armed and armoured the Grey Knight will be carried out to the Dead Fields, accompanied by a handful of his brothers and dozens of Chapter serfs chanting prayers for his departed soul. The Dead Fields are a vast frozen tomb at the foot of Mount Anarch, beneath the large Temple of the Emepror, its chambers and alcoves carved from the cold, dead rock of Titan. The dead Grey Knight is sealed in this icy grave beside thousands of his fallen kin, where he will rest as long as the citadel stands. Often when a Grey Knight perishes his body will be lost to the Chapter, torn asunder by Daemons or incinerated in the baleful fires of the Warp. In these cases the Grey Knight's burial armour will be interred in his place, the empty silver suit grasping a blade bearing the Space Marine's name. As a final tribute to those members of the Chapter that have given their lives in the defence of the Imperium, the names of the dead are carved ceremoniously into a great basalt wall in the heart of the fortress. Among these names are some of the Imperium's greatest heroes, who died in the most horrific circumstances imaginable battling the Forces of Chaos. And like all other matters in regard to the Grey Knights, they will remain almost completely unknown to the rest of the Imperium because of the official policy of denying the existence of Chaos and its daemonic agents to the galaxy at large.
- Deimos - The war needs of the Grey Knights call for a constant supply of ammunition and ordnance. Long ago the Chapter made alliance with the Adeptus Mechanicus and as part of their bargain were gifted with the Forge World of Deimos, known as the Steel Forge. Formerly one of the moons of Mars, the planetoid was dragged across the system to hang in the sky above Titan, its mass mined and converted until it was more star fort than celestial body. The Tech-Priests and Servitors of Deimos serve the Grey Knights alone, crafting everything from Bolters and bolt shells to Stormravens and Land Raiders. Only the Nemesis force weaponry is created in the citadel by the Grey Knights themselves; all other materiel is ferried down from Deimos in an endless stream of heavily guarded transports. Servitors oversee the packing and transportation of everything destined for Titan, loading consignments in utmost secrecy to ensure that no one, not even the tech-magos of Deimos know the extent of the Grey Knights arsenal. The same servitors are then mind-wiped before their return to Deimos, lest the enemies of the Imperium were ever to dissect their shrivelled brains.
- Fallen Dagger Hall - The Fallen Dagger Hall is a chamber that serves as a place for close combat training for the Chapter's Neophytes, conducting drills and sometimes as an informal meeting place with Inquisitorial representatives of the Ordo Malleus. This chamber was so-named because Grand Master Kolgano, centuries earlier, challenged the Grey Knights under his command to an unarmoured dagger duel and promised his jewel-encrusted suit of Terminator Armour to anyone who could beat him. Kolgano is long gone, buried unbeaten with his dagger deep in the heart of Titan's catacombs, but the hall remained lofty and echoing.
- Hall of Champions - The huge central chamber of the citadel is known as the Hall of Champions, a place where the Grey Knights gather to celebrate their victories and hang their trophies where the entire Chapter can gaze upon them. Statues of ancient heroes and glorious Grand Masters look down upon all who enter the hall, their silent, stone stares speaking of great heroism and impressive victories. Ten thousand years of triumphs and trials against Daemonkind are recorded on the walls of the chamber, spelled out in torn, bloody banners, rune-encrusted skulls and the fragments of shattered swords. Each statue, artefact and icon represents a terrible campaign or crusade, often still stained with the gore of those creatures that were banished and those that died in the banishing. Paladins, the Chapter greatest warriors, frequent the Hall of Champions more than any other members of the Grey Knights. These great and glorious warriors gather here to honour their ancestors and their peers, relating deeds past and present in solemn rituals dedicated to the Emperor. It is considered right and just that the new generation of heroes should stand to account under the stony gaze of the old. During these ceremonies battle-brothers will speak to the statues of the champions, offering up oaths and binding vows to prove themselves worthy. On rare occasions these acts of devotion seem to elicit a response; the chamber darkens and torches gutter as if caught in a sudden wind, and the shadows playing across the faces of the statues bring the carvings to life. What a battle-brother sees in those cold stone faces is for him alone to know. The Hall of Champions is not just a place to honour heroes past, but also heroes present. When the Grey Knights defeat a great foe or mark an important event in their history this is where they will congregate. Over the centuries the hall has echoed countless times to the sounds of Grey Knight battle-brothers reflecting on their victories. After cleansing the daemonic forge world of Cebrum II and slaying its Daemon Magi, the Grey Knights gathered in the hall, hanging the thirteen twisted iron masks of the Magi on the wall to mark their triumph. When the Grey Knights sealed the void well on Capulos, ending the 1,001 days of night, they brought back a fragment of the jade capstone used to close the breach as a symbol of their victory. Perhaps the one of the greatest trophies of the Hall of Champions is the skull of Iremn'ath. The Daemon Rajah of Nalu, Iremn'ath was one of the few creatures to penetrate the outer circles of the Ibb worldmaze. Fear of the Daemon reaching the sacred Heart of Ibb prompted the Grey Knights into a long and costly battle to vanquish the Daemon. For a year an entire brotherhood of the Chapter hunted Iremn'ath's minions through the labyrinthine streets of Ibb, vanquishing his lieutenants and casting down the cults raised in his name. When at last the Grey Knights defeated the Daemon Prince, they bound his spirit to his skull. Since that day Iremn'ath has hung on the wall of the Hall of Champions, bound with wards and glyphs as scores of acolytes endlessly chant the spells that keep the Daemon imprisoned. From his vantage point upon the wall, Iremn'ath is forced to watch the triumphs of his foes and their victory rituals while he seethes with hatred and silently howls within a prison of bone and sorcery.
- Mandulian Chapel - This chapel consisted of a long gallery with a dizzyingly high ceiling, thick with columns and with statues in niches running along the walls. To reach the huge, three-panelled altar at the front of the chapel, a Grey Knight had to walk past the unwavering stone eyes of hundreds of Imperial heroes. Some of them were legends, some had been forgotten, and they represented every part of the web of different civilian and military organisations that kept the galaxy-spanning Imperium together. Closest to the altar was the statue of Grand Master Mandulis himself, who had died a thousand standard years before the late 41st Millennium -- his figure carved into one of the pillars as if he were holding up the chapel's ceiling -- a clear symbolic message that Mandulis, like every Grey Knight, kept the Imperium from collapsing.
- Sanctum Sanctorum - Deep in the heart of the citadel lies the Sanctum Sanctorum. Behind triple-ealed portals, bound with forgotten science and Warp-magicks, the Sanctum keeps safe the Grey Knights' many psychic secrets. The towering shelves of time-worn tomes, crumbling scrolls and fragmented data crystals are tended to by the Chapter's Librarians; each of these honoured battle-brothers oversees a different section of the Sanctum, and specialises in a different part of the Grey Knights' history or lore. Assisting the Librarians are queues of shuffling hunchbacked servitors –- their lobotomised brains wiped and reprogrammed at the end and start of each day. The Sanctum contains every secret of the Warp known to the Grey Knights, a galaxy of forbidden knowledge painstakingly gathered over thousands of years. Not even the data vaults of the Scholastica Psykana on Holy Terra can rival the archives held in the Sanctum. They contain the carefully guarded knowledge of how to fashion Nemesis force weapons -– an ancient technology said to have been created by the Emperor himself specifically for the Grey Knights, and a secret the Chapter has kept safe since the time of the Heresy. It is even rumoured that the Grey Knights have other writings of the Emperor, tomes that still bear words written in his hand, detailing what Humanity has learnt of the Warp and what was lost during the Dark Age of Technology.
- Librarium Daemonica - Perhaps the most important chamber within the Sanctum Sanctorum is the Librarium Daemonica. The room contains the names of every Daemon encountered by the Grey Knights and everything the Chapter knows about the Dark Gods and their agents. For this knowledge ever to leave Titan would be a disaster of unimaginable proportions. If the enemies of the Grey Knights were even to learn of the room's existence, it could spell doom for the Chapter. To protect such a valuable place, the room lies in the very centre of the Sanctum, encased with adamantium walls, floor and ceiling metres thick and bound with esoteric wards and layers of Void Shielding. A single passage leads into the chamber, its length barred by three doors. The first is a hulking blast door heavy enough to resist a continual barrage of melta fire, and sealed with a cipher-lock with almost infinite combinations. The second portal is a spatial displacement field, an artefact of ancient science that bends space back upon itself. A foe trying to breach the field will find his weapons turned back upon him, and no matter how fast he runs he will end up where he started. The final door is a magickal vortex, proof against Daemons and psykers both. A being even weakly connected to the Warp that tries to cross the vortex without speaking the right words of power will have their soul ripped away. Before each of these doors a Grey Knight Librarian kneels in meditative silence, resting his arms upon the pommel of his blade until someone draws near, at which point he will rise to his feet, ready to strike. A trespasser has but a moment to speak the secret words that will send the Librarian back to his vigil, or his life is forfeit. The Guardian Librarians are specially chosen for their single-minded dedication and know not to trust the appearance of any that come before them, whether or not they wear the guise of a Grey Knight or even the face of a dear brother.
- Vault of Labyrinths - In one corner of the Sanctum Sanctorum lies a stasis vault, a time-sealed prison from which there can be no escape. Within the vault lie scores upon scores of Tesseract Labyrinths, fist-sized cubes of an alien design recovered from what are now recognised as unawakened Necron Tomb Worlds across the galaxy that are capable of imprisoning beings of pure energy, amongst whose ranks daemons can be counted. Over the millennia, the Grey Knights have succeeded in sealing a few dozen daemons within the extradimensional chambers of Tesseract Labyrinths, thus weakening the daemonic threat by a miniscule degree.
- Warp Nexus - The Warp Nexus is a star-shaped chamber that lies at the very heart of the Grey Knights' fortress-monastery. The very air within throbs with shackled power. Fuelled by the ceaseless chants and prayers of two hundred Chapter Serfs, it was the mandalas and pentagramic sigils of the Warp Nexus that maintained Titan and the Chapter fortress amongst the turbulent tides of the Immaterium during their time of preparation after the Horus Heresy. In the ten millennia since, much effort has gone into maintaining the Warp Nexus. In part, this is simply because it is one of the few tangible artefacts left behind by Malcador the Sigillite. This is underpinned by the more practical goal of attempting to realign the Warp Nexus' power once again, ensuring Titan has an unassailable refuge in the Empyrean should it be required.
- Codex: Daemonhunters (4rd Edition)
- Codex: Grey Knights (7th Edition), pp. 18-26
- Codex: Grey Knights (5th Edition), pp. 8-9
- Warhammer 40,000: Dark Millennium (1994), pg. 22
- White Dwarf 260 (Australian Edition), "Index Astartes - Purge the Unclean"
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