Grey Knights Librarian - Role: All Grey Knights possess a degree of psychic ability which is further developed and enhanced by their years of training on Titan. While only a handful of Battle-Brothers ever achieve the levels of power commanded by the Chapter's Librarians, they are all capable of manifesting certain powers and abilities, especially in the company of other Grey Knights where they can combine their gifts to create great effects and more devastating psychic attacks.Grey Knights do not suffer the corruption of the Warp and are nigh invulnerable to its longer-term effects. While daemonic forces may effect them physically, or even confuse them, they are the purest of Space Marines and the most resistant to the powers of the Empyrean. Grey Knights are far less susceptible to insanity than normal men and their constant exposure to daemonic horrors and foul Warp sorcery hardens them against the worst of its effects.To be a Grey Knight is to constantly face madness, death, and far, far worse. To fuel their supernatural abilities, Grey Knights draw on the limitless potential of the Immaterium. However, the Warp is anathema to humanity, filled with predatory creatures and malign intelligences. Should a Grey Knight drink too deeply from the Warp’s power, he runs the risk of attracting the unpleasant attention of its denizens.A psyker as well-trained and pure as a Grey Knight learns how to mask his presence from the creatures native to the Warp. He can moderate, or fetter, his powers, reducing the amount of Warp energy he channels through his mind. Doing so has the drawback of reducing the sheer power of his abilities, but his presence does not stand out amongst the Warp's chaotic, shifting tides of energy.Of course, sometimes caution must be forsaken if the circumstances are dire enough. Just as the Grey Knight can temper the power he taps from the Warp, so can he exceed his limits and gather as much as his psyche can hold, and more. This is known as "pushing," and both the results and the consequences can be truly impressive.Grey Knights train to fight as small units in battle. Each member of a squad supports the others with close combat attacks and well-placed Bolter fire. This unity of purpose and high level of training extends to their use of psychic powers, and Grey Knights have developed the ability to manifest their abilities by tapping into the psychic potential of the Battle-Brothers around them. Grey Knights may only combine their psychic powers with other Grey Knights; they cannot include any other kind of psyker who is not trained in their specific methods, including other Space Marine Librarians.On the battlefield, Grey Knight Librarians use their powers to support their Battle-Brothers. This often manifests in a display of raw psychic might, such as a cataclysmic Warp rift or bolt of eldritch lightning. Yet it is perhaps the Librarians' subtler powers that have the most effect.With a little effort, a Librarian can summon others to his side, cloak them in protective shadow, or imbue them with great strength. Little is beyond a Librarian, for in the Sanctum Sanctorum is recorded every conceivable psychic ability, sigil of power and sorcerous incantation, and it is from here that the Librarian chooses his weapons for the battles to come. Thus is a Librarian amongst the Chapter's most versatile warriors.Yet for all the contributions a Librarian can make to a Grey Knights strike force, his most vital tasks are carried out within the walls of the fortress-monastery on their Chapter homeworld of Titan. It is here that the Librarian will school new recruits in the mysteries that all Grey Knights must know: the six chants of denial, the seven words of life and death, the eight songs of battle, the nine terrible spells that form the basis of all magick and much more besides.A Librarian's tutelage is a most rigorous process, and many Aspirants do not survive, for it is better for a weak recruit to perish at a Librarian's hands than for him to imperil the Chapter through his inadequacies. Yet if the Librarians are called upon to be ruthless, there is little cruelty in their actions, and no malice. This culling of the weak is merely a necessity -- for the Grey Knights to remain incorruptible, they must be as hard of mind and will as they are of body.A few Librarians are fortunate enough to reach an age when their bodies can no longer meet the rigours of campaign. Such warriors are removed from the Chapter's fighting roster entirely, and retire to the labyrinthine corridors of the Sanctum Sanctorum of the fortress-monastery on Titan to take up guardianship of its musty crypts. Only these ancient ones know the full catalogue, for there are some secrets buried therein of which even the Grand Masters are ignorant. Such mysteries can never be allowed to escape the confines of the Sanctum Sanctorum, for the fear is ever that even some amongst the Grey Knights would not prove immune to their temptations.