Adeptus Astra Telepathica - League of Blackships: During the Great Crusade and Horus Heresy eras, the Divisio Astra Telepathica possessed a militant arm which was referred to internally within the records of the Adeptus Terra as the Departmento Investigates. But they were known throughout the galaxy as the Sisters of Silence, the Silent Sisterhood and the Witchseekers.The Silent Sisterhood was an all-female Imperial order of Witch Hunters dedicated to the elimination of psychic threats to Mankind. Their primary base of operations was the Somnus Citadel on Luna, the moon of Terra. Their purpose was to hunt and kill rogue Human psykers whose activities presented a terrible danger to the people of the newborn Imperium of Man.The Sisters of Silence were well-trained warriors, and with the added benefit of their natural and innate anti-psyker abilities they were dangerous opponents to the psychic enemies of Mankind. Unlike other living beings, these women sworn to silence possessed no presence in the Warp and were therefore unaffected by all forms of psychic power.There were many names for them in the multitude of Human cultures to be found across the galaxy: Untouchables, Pariahs, Blanks, psychic Nulls. All of the members of their order were non-psychic, for they bore the Pariah Gene which made them immune to all forms of psychic assault and rendered their minds unreadable by telepathy.The sisters operated the Astra Telepathica's infamous Black Ships, which ranged across the galaxy following behind the Great Crusade's expeditionary fleets in search of Rogue Psykers to capture or expunge, seeking to collect and carry them back to Terra where they would be tested and their eventual fate decided.Though few in number, the Sisters of Silence commanded great respect within the Imperium and most servants of the Emperor regarded them with some awe. Few would willingly stand in their way or interfere with their activities and few indeed were those who were comfortable in their presence.After the Horus Heresy, it was long believed that the Sisters of Silence were either destroyed long ago or were ultimately folded into the organisation of the Imperial Inquisition. They disappeared from Imperial history for nearly 1,500 standard years, until the Imperium faced annihilation at the hands of the massive Ork WAAAGH! led by the warlord known only as The Beast in the 32nd Millennium. The last vestiges of the Silent Sisterhood would play a key role in defeating this Ork WAAAGH! and diverting disaster.Though officially disbanded after the Age of Apostasy in the 36th Millennium, many enclaves of the Silent Sisterhood still fought for the Imperial cause, albeit in a more secretive and elite capacity than before. With the resurrection of Roboute Guilliman as the lord commander of the Imperium and Imperial Regent after the birth of the Great Rift in ca. 999.M41, the Silent Sisterhood has begun to serve more openly alongside Imperial military forces such as the Indomitus Crusade once more. Though still small in number, it is now possible once again to see one or more of the Sisters of Silence accompanying the Black Ships on their vital duties.In the 41st Millennium, where the strict anti-psyker strictures of the Council of Nikaea were long ago partially relaxed following the reformation of the Imperium in the wake of the Horus Heresy during the Time of Rebirth, the League of Blackships now forms the recruiting division of the Adeptus Astra Telepathica.The League consists of a substantial fleet of black Imperial starships charged with collecting and transporting psykers taken from worlds across Imperial space as part of the Imperial Tithe to Terra. The Black Ships are feared transports filled with mournful psykers held in cavernous, psi-shielded holds to be taken back to Terra to feed the voracious psychic appetite of the Emperor in an ongoing attempt to maintain the power of the Astronomican's psychic beacon. Only those psykers with the strength of mind to withstand the constant soul-numbing despair that permeates the Black Ship may crew it, so mentally traumatic is such duty.The Black Ship fleet travels constantly throughout the Imperium. Each Imperial world is visited every one hundred Terran years or so by a Black Ship. When a Black Ship nears an inhabited Imperial planet, its planetary governor is instructed to prepare the customary levy -- a tithe of psykers.Once the levy has been collected, the Black Ships' captains make an initial evaluation of their cargo before proceeding to the next world in their circuit. When the ships are full they return to Terra and the psykers are transferred to the Scholastica Psykana before the ship leaves again to continue in their eternal search for new psykers.It is common for Inquisitors of the Ordo Malleus or Ordo Hereticus to travel aboard the Black Ships, as this gives them a good opportunity to investigate a planet's potential for psychically-based corruption.