Librarian - Codex Librarians: Each Chapter selects its Librarians in its own way, either from seed worlds, as it does with the bulk of its Initiates, or from the ranks of gifted psykers brought to the Scholastica Psykana. Most Chapters train and test chosen psykers following the ancient ways laid out in the Codex Astartes.Librarians of the Ultramarines, Blood Angels, Dark Angels, and Storm Wardens are all trained in this way, and, with few minor traditional variances, have been taught to live by the word of the Codex. There are, however, a few notable Chapters that do not follow the Codex Astartes and its laws regarding the treatment and control of psykers, including the following.Black Templars - Deeply religious and reverent of the Emperor, the Black Templars are zealots with a deep and abiding hatred of the witch. Such is their disdain of those with psychic powers that they count no Librarians amongst their number lest they foul the Chapter's pristine gene-seed. The tasks of the Librarian, such as record-keeping and the study of lore, are divided among scholarly battle-brothers without the taint of the witch within the Chapter. Often an individual Black Templars Space Marine or Chapter Master will be responsible for maintaining a record of his own deeds—inscribing them on his armour so that nobody may doubt his courage or lineage.Space Wolves - There are few things that are "standard" about the Sons of Leman Russ, and so it is no surprise that they treat their psykers differently than the rest of the Adeptus Astartes. The Space Wolves do not have Librarians or even a Librarius, scorning such dusty and lifeless collections of knowledge. Instead they adhere to the ancient Fenrisian traditions of their ancestors, and those with psychic gifts become Rune Priests—skalds and storytellers who keep the Chapter’s practices and history alive through millennia-old oral traditions. While Rune Priests use their own powers and train in their own way, they function much as other Space Marine Librarians do, tapping into the Warp and drawing forth power to create psychic effects and reshape reality.White Scars - The Zadyin Arga or "Stormseers" of the White Scars perform the same functions as other Chapters' cadre of Librarians, though the Stormseers emerge from the deeply-ingrained mystical traditions of the tribal shamans and holy men who rode the plains of Chogoris with their Primarch Jaghatai Khan before the coming of the Emperor to Mundus Planus. Since the time before their Chapter's inception, when they were the shamans who first named Jaghatai Khan the Great Khan of the nomadic tribes, the Storm Seers have been called upon to continue to induct Neophytes and newly elevated Khans of their Chapter. The other responsibilities of the Storm Seer include teaching Aspirants the core beliefs of their Chapter. They firmly believe it is the manifest duty of the White Scars to destroy the enemies of the Imperium, awaiting the day that that Emperor will rise again, signaling the return of their lost Primarch and the beginning of the next Great Crusade to unify all of humanity. The Storm Seers believe that their powers are connected to the animistic spirits of the land and the air, and that as long as these natural forces fight alongside them, the White Scars will always be victorious. These elemental, animistic beliefs and the highly stylized Force Staff used by Storm Seers tie these warrior-mystics to their shamanistic past on the steppes of Mundus Planus.Grey Knights - 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 Grey Knights 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. However, those who prove to have a strength of mind far greater than that of their fellows will go on to join the ranks of the Chapter's Librarians. The Grey Knights have many abilities that standard Space Marines lack. These powers are psychic in nature and work on a gestalt principle much like that of the Orks in which the more Grey Knights that are present in one location, the more powerful their psychic abilities become. Besides these powers, the Grey Knights are highly-skilled close combat fighters. Most Grey Knights who are masters of melee combat are able to win against even the most seemingly impossible of odds. Unlike Space Marine Librarians or other psykers, their power is deemed free of the taint of the Warp and they are the only psykers allowed, for instance, in a Crusade army of the Black Templars Chapter.