Magnus the Red - Council of Nikea: Magnus fought bravely and successfully during the Great Crusade, but he was always a wild and impetuous commander. Magnus had an inherent affinity for the Warp and the secrets hidden within its fabric. Throughout the Crusade he came into contact with long-isolated human cultures scattered on worlds across the galaxy where psykers had been allowed to flourish. Although warned by the Emperor to shun such matters, Magnus began to gather arcane lore about the practice of sorcery from other cultures across the galaxy. From this material he compiled the monumental tome of sorcery and psychic practice known as the Book of Magnus. The book, whose simmering covers, inscribed with strange wards, were made from the psychically-active hide of a slain psychneuein, was always fastened to Magnus' armour with a heavy gold chain, kept closed by a lock made of lead.One of the things Magnus discovered during his 28th Expeditionary Fleet's conquests was the existence and nature of the Eldar Webway and of the realspace portals into it. However, his knowledge of the Webway's geography and functions was incomplete and fragmented -- a fact that later cost him dearly. Nevertheless, he managed to enter its star-spanning corridors by brute psychic force.The further from Terra the Great Crusade's fleets travelled, the more strange Warp-influenced creatures they came across. This naturally made Magnus look suspicious to his fellow Primarchs, as his control over the Warp and the sorcerous powers he derived from its chaotic energies were very similar to the abilities displayed by these malevolent creatures. The Space Wolves' Primarch Leman Russ and the Death Guard Primarch Mortarion both distrusted Magnus due to his and his Legion's use of the powers of the Warp and because of his mastery of deceit in warfare where they preferred a more straightforward use of physical strength and brute force. Another point of contention between the Primarchs was the Thousand Sons' love of knowledge in general; they always sought to preserve and study the knowledge of newly Compliant worlds, carrying libraries' worth of material on the 28th Expedition's starships for eventual archiving on Prospero. The other Astartes Legions found this obsession with the collection of knowledge -- whatever the source -- counterproductive to the goals of the Great Crusade which sought to spread the specifically Imperial strain of human civilization across the galaxy. They also believed it to be dangerous because of the malevolent nature of so many of the beings that lived within the Immaterium.During a joint mission between the Thousand Sons and the Space Wolves Magnus and Leman Russ came close to blows over this issue, and over the use of psychic powers in general. Bloodshed was avoided only thanks to the last minute intervention of Lorgar, the Primarch of the Word Bearers. Over the following decades, other Primarchs voiced their displeasure that these so-called psyker Astartes were allowed to exist and serve the Emperor's righteous Great Crusade. Rumours and condemnations began to spread about the Thousand Sons Legion amongst the other Expeditionary Fleets. The most vocal of these detractors were the Primarchs of the Death Guard, Imperial Fists and Raven Guard Legions. Soon the Thousands Sons' detractors raised their objections to the Emperor himself, calling for the XVth Legion's disbandment and for the Legion to be expunged from Imperial records like the IInd and XIth Legions.However, serious suspicion began to surround Magnus as the hatred towards mutants and psykers spread through the Imperium as the Crusade progressed and the Legions learned how dangerous the use of psychic abilities could be on world after world that had been ravaged by them during the Age of Strife. After much debate in the Imperium over the use of psykers, the Emperor called an Imperial Conclave of all the Primarchs and chief Imperial officials at the remote and volatile planet of Nikaea to deal with the issue once and for all. The highest authorities in the young Imperium were present or were represented, including the Emperor and his Sigillite and Regent Malcador, who officiated over what became known as the Council of Nikaea. At the forefront of the debate was Magnus, who argued very passionately for his cause and the important contributions that psykers and the use of sorcery could make to the improvement of the Imperium and to speeding up the successful conclusion of the Great Crusade. The main opponents to the use of psykers were the Space Wolves who shared their Primarch Leman Russ' hatred of sorcery as unclean and cowardly and the Death Guard, whose Primarch Mortarion testified in person against the use of psychic powers because of his experience with the psychic warlords who had ruled his own homeworld of Barbarus.When a consensus emerged amongst the Council's participants that psykers and their powers represented a potential danger to the people of the Imperium, the Emperor ordered that in the interest of unity, no one was to be censured for prior actions involving the use of psychic abilities. Use of psychic abilities by the Imperium's military forces was banned (except for Astropaths, Navigators, and very strictly sanctioned and controlled psykers who were authorised to carry out Imperial business). All the Librariums employed by the Astartes Legions were to be disbanded, and their members returned to conventional combat duty, enjoined from ever again using their psychic gifts.In effect, Magnus and the Thousand Sons were banned from practicing "sorcery" or using the psychic abilities and knowledge they so coveted. The edicts of the Council of Nikaea also created a new position amongst the Space Marine Legions, the Space Marine Chaplain, to uphold the Imperial Truth and help maintain the purity of an Astartes Legion's dedication to the Emperor's commands. Disappointed and unhappy with the decision, Magnus was forced to accept the new prohibitions on sorcery in the Imperium, but he soon tried to find rationalisations and justifications to circumvent it.