Sorcerer - History: During the early years of the Great Crusade many Astartes of the Space Marine Legions began to display powerful psychic abilities. One such Legion where psychic powers were particularly prevalent was the Thousand Sons.The Astartes of the XV Legion welcomed this development, for they sought to further emulate the Emperor of Mankind. This development was reluctantly tolerated by the Emperor, who was greatly wary of psychic abilities wielded by anyone other than Himself or Malcador the Sigillite, though the Thousand Sons' abilities proved to be a powerful weapon for the Imperium during the Great Crusade.At the urging of Magnus the Red and some of his fellow Primarchs, this led to the creation of the Librarius corps within each Legion, whose psychically gifted Battle-Brothers would seek the betterment of their Legion and the expansion of the burgeoning Imperium of Man.Throughout many of their campaigns the Thousand Sons made extensive use of sorcerers, and their Warp-derived powers would leave whole populations in thrall to their will rather than carrying out a planetary conquest through a costly full frontal assault like the other Space Marine Legions.This tactic earned the ire of Leman Russ of the Space Wolves Legion who saw anything less than a frontal assault as dishonourable and cowardly. Over the following solar decades some of the Primarchs voiced their concern that these so-called "psyker" Astartes were allowed to exist and be a part of the Emperor's 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.These tensions finally came to the fore when the Emperor called for the Council of Nikaea, a great Imperial conclave held on the world of Nikaea in the midst of the Great Crusade that was intended to determine whether or not the use of psychic sorcery 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 required dealing with the beings of the Warp and was defined as sorcery was officially banned.The Emperor was most displeased by the Thousand Sons' dabbling in manipulating the corrupting powers of the Warp and later forbade the use of sorcery by either Magnus the Red or the members of his Legion.But the psychically powerful Magnus and his Thousand Sons would continue to study such powers in secret on their homeworld of Prospero, ultimately leading to their damnation by Chaos, and the scouring of their world by the Space Wolves, unleashing a deadly rivalry that has lasted unto the present day.During the Horus Heresy, the Librarians of those Traitor Legions that spat on their oaths of fealty to the Emperor and dedicated themselves to Chaos received new psychic powers.The only exception were the Librarians of the World Eaters, who were hunted down and slain by their brethren as a bloody sacrifice to Khorne, for the Chaos God of war and murder hates all practitioners of sorcery, which he sees as dishonourable trickery when compared to the joys of simple, blood-drenched slaughter.It is not only the servants of the Ruinous Powers who have been tempted to draw upon sorcery. For those who already tread a fine line between righteous power and damnation like Space Marine Librarians, the temptation to wield the energy of Chaos for selfish means can be overwhelming.It is for this reason that the Emperor once sought to ban the use of all psychic powers, fearing that no Human being save Himself could be trusted to wield such powers without falling to corruption by the Warp. Although all Librarians are tested for the mental fortitude to withstand Daemonic possession and the lures of the Dark Gods, and are constantly monitored by their Chapter, there are those who still succumb.The line between the basic use of psychic power and what constitutes "sorcery" is blurred, and every time a Librarian or any psyker uses his powers he is risking corruption. He may overreach his abilities, unwittingly drawing on more power than he can control, and by these means attract the attention of the Chaos Gods.From that moment, he must endure cold whispers in his dreams, visions of immortality and promises of untold power. There are those who cannot withstand this incessant temptation, and fall to Chaos.These tragic characters are amongst the most iconic archetypes of Chaos for they have embraced the Ruinous Powers in open defiance of the dictates of the Imperium. sorcerers of Chaos are vilified and feared, and one of the most hated foes of the Imperial Inquisition, who consider them the most severe of blights upon the galaxy.Unrestrained by concerns about corruption or morality, a Chaos Sorcerer's powers can be used to destroy through the most flamboyant and pyrotechnic means imaginable. Chaos Sorcerers can hurl bolts of raw Warp energy at the enemy, curse them with Nurgle-spawned plagues and diseases, animate their dead bodies as flesh-eating zombies or physically shape-shift them into a formless blob of flesh.Most Chaos Sorcerers bear the Mark of Tzeentch, who is the Changer of the Ways and the Chaos God of Sorcery, but sometimes sorcerers bearing the Marks of Nurgle the Plague Lord or Slaanesh, the Prince of Pleasure, also appear.Khorne despises the use of sorcery rather than brute physical power and will specifically obliterate any psyker who would beseech him for power, thus no sorcerers appear in his service. The Traitor Legion with the most powerful sorcerers is still the Thousand Sons, who are wholly dedicated to the service of the Changer of Ways.The primary difference between a true sorcerer and a standard psyker is that the former draws much of their power from dark rituals, Daemonic pacts and unholy incantations which all draw to some extent on the power of Chaos. Even a person without any psychic gifts can become a powerful sorcerer through the use of Warp lore, but this process is fraught with terrible dangers to both body and soul.Such Heretics constantly seek out additional sources of esoteric and forbidden information. They have studied a broad array of arcane knowledge, including xenos practices, legends, and secrets long thought lost. No targets or types of data may be off-limits.While sorcerers are likely to favour arcane knowledge tied to the dark arts, they realise that the Ruinous Powers may have uses for seemingly mundane bits of data. Virtually any information is useful as it could be enough to persuade their sponsors within the Warp to empower them yet further. The notion of forbidden knowledge is anathema to these Heretics, as they know that their personal destinies transcend any mortal strictures.An actual psyker can drastically increase his powers by using the dark arts, but at the same time the sorcerous practitioner becomes more vulnerable to the perils of the Warp. Sorcery has been strictly forbidden on many worlds since even before the foundation of the Imperium of Man and the edicts against it made by the Council of Nikaea, but its power still lures thousands of Chaos Cultists to their damnation every Terran year.Even amongst the servants of the Emperor of Mankind, such as Inquisitors of the Radical philosophical persuasion, there are some who believe that sorcery can be used for the betterment of Mankind, as Magnus the Red once did.Most sorcerers of Chaos are members of a larger warband of Heretics or Chaos Space Marines. This can lead to conflict within the warband, as the sorcerer is rarely willing to accept the commands of the Chaos Champion who serves as its leader, unless that leader has the force of will and strength of arms to maintain an iron command.Many warbands have splintered when a sorcerer of Chaos attempted to take command, leading a portion of the members towards a goal distinct from that of their Chaos Lord. This may even result in the warlord's death, reminding his fellows of the risk of maintaining such a powerful individual as an advisor.