Astra Militarum - Psykers in the Astra Militarum: Ruinous power. Highly destructive capabilities. A wild card, capable of turning the tides of war. These are the thoughts of many in the Departmento Munitorum when the idea of psykers comes into their minds. For the troops that must serve alongside these beings, they are enigmatic monsters drawing upon eldritch forces, kept in check only by the steady shot of a Commissar’s Bolt Pistol. Psykers are feared throughout the Imperium with good reason. On Feral Worlds, witches conjure demonic power and break all laws of nature. On more civilized worlds, those who are shown to be psychically active rarely have the time to even realise the power they hold before they are captured and taken to the dreaded Black Ships. From there, they either prove themselves useful enough to serve where needed, or prove too wild and dangerous to be allowed to live; those that come up wanting are taken to Terra. Once there, they will join tens of thousands more psykers in giving their souls to sustain the God-Emperor for another day.While psykers are feared and distrusted throughout the Imperium, the empire of Mankind could not function without them. Psykers are the links that hold the human-settled galaxy together -- psychic communication is the only means the Imperium has to communicate over the vast distances of space. Astropaths relay orders, allowing the sweeping force of the Imperial armies to spread across the galaxy. Without psykers, the Imperium would fall apart, with all of the many worlds Man has claimed being unable to communicate with even the lords of their sector. However, every psyker is also a grave danger to those around them. Each psyker is a gateway through which the daemons of the Warp may enter the material world and bring destruction to Mankind. Thus, the collection and training of those who show signs of this power is a serious -- and often brutal -- undertaking. Those who brandish the power of the Warp in the hopes of building cultish power often meet very swift ends at the hands of dreaded Inquisitors.However, those who prove useful may be put to work for the benefit of Mankind. Clever and competent Wyrdvane Psykers (Sanctioned Psykers) may be put to use by the Imperial Guard, or find a place in the Imperial Navy, giving Imperial commanders advice pulled from the Aether. Particularly wily and talented psykers may be called in to serve the Inquisition. Many psykers are branded and marked, ensuring that they may be easily identified and punished for any unusual activity, wherever they may be.Psykers play an important role amongst the ranks of the Imperial Guard. Gathered into large psychic choirs, a group of psykers can weave their power together to perform extraordinary feats. As they gain experience, psykers can even ascend to the rank of Primaris Psyker, accompanying Imperial commanders into battle and summoning incredibly destructive powers to turn the tides of battle. These potent individuals are viewed with a mix of fear and awe by the general ranks of Guardsmen, and having a psyker attached to an Imperial Guard squad can raise tensions considerably.The Imperium needs psykers, but only those who can use the unstable powers of the Warp for the good of Mankind. When the seed of power is found on any Imperial world, they are gathered, sedated and sent away on board the dreaded Black Ships. They are tested, and those found worthy are selected to attend the revered Scholastica Psykana, where they may learn to control their power. Out of these countless psykers, only a very small percentage will leave alive. Most meet their end in the deadly training, or are executed by the overseers when their power exceeds their control. If they are to control the energies of the Empyrean, they must first learn its true nature. Many are driven mad when they first look into the roiling energies of the Warp, and see it staring back at them. Those who survive their trials may become Sanctioned Psykers.Once sanctioned, a psyker may be approached by certain powerful individuals, if they have shown exceptional power and control. For most Sanctioned Psykers, they will get their chance to serve the Imperium and prove their loyalty to the Emperor amongst the ranks of the Astra Militarum.Psy Rating (PR) is a raw measure of a psyker’s power and his ability to draw power from the Warp. The higher a psyker's PR, the more powerful he will be. PR usually ranges from 1 (a novice Imperial psyker or petty Warp-witch) to 10 (a monstrous Greater Daemon or masterful Eldar Farseer), though in some extremely special cases it may go higher still. A starting Sanctioned Psyker of the Astra Militarum usually has a Psy Rating of 2, with a Primaris Psyker reaching 5 or 6 at the height of his power. Sanctioned Psykers' individual relative weakness is the reason why they gather in Circles when in service to the Guard, as their combined power allows the Circle to face off against a truly powerful psyker and prevail where each Sanctioned Psyker individually would be swept aside.Unfortunately for the Guardsmen fighting the Imperium's wars, the psykers of the Imperium are not the only beings in the galaxy who can wield the foul powers of the Warp. From mysterious Eldar Farseers and vicious Chaos Sorcerers, to unpredictable Ork Weirdboyz and the ominous Zoanthropes of the Tyranid  Hive Fleets, powerful psychic individuals stand amongst the ranks of almost all of the enemies of Mankind. Simply seeing the destruction that can be wrought by these individuals can drive a Guardsman mad.