| Proclamation of made by the [[Emperor of Mankind made ]] during the Council of Nikaea which decreed that the [[Legiones Astartes]], beyond the use of [[Navigators ]] and [[Astropaths]], would no longer employ [[psykers]]. They were to disband their Librarius departments, the Librarians re-deployed to the battle companies and the primarchs themselves were to refrain from using any psychic powers they possessed.