During the early days of the Great Crusade there was a great conclave called by the Emperor of Mankind known as the Council of Nikaea. This conclave was intended to determine whether or not the use of psychic abilities represented a boon or a grave danger to Mankind and the newborn Imperium of Man. Ultimately the existence of psykers in the Imperium was allowed but tightly restricted under centralised Imperial control, while the potent and unrestricted use of psychic abilities that was defined as sorcery was officially banned. This Decree Absolute was a command of the Emperor Himself, a warning about the dark potential for corruption that was implicit with the use of the powers offered by the Warp. This was a command that the Primarch Sanguinius echoes, to forbid the use of preternatural p