Psykers are those blessed with the curse to use psychic powers. Each race tends to have their own unique individuals and methods to tap the warp. The ability isn't one that simply be learned - you are either born with the abilities or not. Psykers aren't always looked upon with favor; The Necron and C'tan races actually produce units which passionately seek out and destroy them. Some races, such as the Eldar, are instinctively psychic. The Warp supplies most of the power from which the psykers tap, save when it comes to the Orks, who draw from their symbiotic-like Waaagh powers.
The mutation of the Psyker ability is becoming more and more common amoungst the Humans, leading some to believe a whole new sub-strand of Humans are drawing ever nearer. Psykers are the ideal creature into which Humans will evolve, a more intelligent, powerful and capable life form - the future of Humanity. While the emerging race is still showing signs of mental weakness when it comes to yielding to the influence of the Warp, they are the ideal representation of both a pro and con to Mankind.
Left unbridled, Psykers pose a potential threat to entire worlds, and as such, much of the Imperial Inquisitions purpose is tracking them down. The Imperium
maintains that Psykers be tracked down, controlled and suppressed; those strong enough to potentially serve are to be enrolled into Imperial service, filling crucial roles as both Sanctioned Psykers and Astropaths, while the weakest look forward to serving Humanity as Adeptus Astronomica, or as life-providing nourishment for the Emperor
- The Inquisition - Inquisitors are far more powerful and exceptional humans, and as such, many are far more potent Psykers.
- Imperial Guard - Represented as the Primaris Psyker and the weaker Sanctioned Psyker, they are the psychic representatives for the Imperial Guard. After undergoing training and education at the Adeptus Astra Telepathicas Scholastia Psykana, they are deemed worthy of service on the battlefield.
- Chaos Space Marines - Since the basic layout of the Chaos armies are mirror images of the Space Marine armies, their role plays the same on the Chaos side, save for the name change from Librarian to Sorcerers.
The Eldar are an inherently psychic race, and as such, some of their strongest units have incredibly strong psychic powers. Warlocks are those Eldar who tread the Path of the Seer, while Spiritseers are their specialized kin. Those lost on the Path of the Seer are deemed Farseers.
Their powers and abilities are typically subtle, ranging from receiving future occurrences, fighting mental face offs, to detecting enemy movements. Although, a Farseer may be able of using their raw telekinetic power to fling a battle tank into thin air.
The Dark Eldar resemble the Eldar in nature, yet have forsaken the utilization of psychic powers. While they do use psychic objects, any Psyker found on Commorragh (the Dark Eldar homeworld) is treated as a mere plaything, ending in intense suffering and torment.
The armies of the Orks make proficient use of psychic powers and abilities. Ork Psykers differ from the rest of the races in that they draw their powers from the collective
Orks, completely bypassing the Warp entirely. Mobs of Orks tend to originate what has since been known as the Waaagh field, which is then absorbed by the Weirdboys - the Ork Psykers. Yet their control is far from complete - drawing too much would result in a massive build up to end in the exploding head of the Ork, causing massive damage to everything in their proximity. Avoiding combat, the Weirdboys do have the defensive ability to cast a green inferno having the ability to melt both armor and warrior within.
Weirdboy powers are vastly unpredictable and often have catastrophic results, yet the positives are typically only seen by the Warboss. Weirdboys are rarely seen in those tribes who have progressed past the feral stage, who instead choose to rely upon the more advanced technology they come upon, no matter how crude.
As the Eldar, the Tyranid forces tend to be highly connected amoungst themselves using their inherent psychic abilities. Acting as the node for the other forces on the ground is the Hive Tyrant, while the Dominatrixes serve as relays between the Norn-Queens and their other ground forces, making things far more efficient when it comes to coordinating attacks from orbiting units.
Spending a good amount of time in the Warp, they use it to enhance both communication and travel in their time between worlds looking for substance. Offensive Tyranid powers are primarily reserved for the Zoanthrope, whose psychic blasts have yet to meet those who withstood their attack.
Inherently a non-psychic race, the Necrons had any psychic potential wiped from their future when their race was destroyed and they made the choice to exchange their organic bodies for metallic forms.
During the C'tan's war against the Old Ones, they were able to turn the tide against the C'tan and the Necrons by bio-engineering whole races of psychic warriors. Lacking the ability to to sense or manipulate the Warp in any way, the C'tan feared the Warp. They gave birth to the psychic abomination known as the Pariah, making life for Psykers hard beyond all measure by interrupting their link to the Warp. Destroyed also were the ancient weapons known simply as Blackstone Fortress, which saw its construction at the hands of the Old Ones, allowing for the release of gigantic psychic waves with the strength to annihilate the C'tan if they should ever make it a point to rise again. Their most ambitious undertaking was a ward engineered to totally seal off the known material universe from the touch of the Warp; yet stasis saw their end before the completion of the project.
have yet to undergo the evolution allowing them contact with their psychic abilities, with a chemical mixture in their mind that looks to cut off contact from the Warp. Not yet known are the reasons this happened only to this race, but it saves the Tau from the taint of Chaos, as non of their units have the ability to touch the Warp.
However the Kroot
and the Nicassar, two allies of the Tau, possess psychic abilities. The Nicassar primarily use their powers for navigation, allowing for their Dhows to escort the Tau Space Fleet
Kroot who have satiated their hunger upon those with psychic abilities may develop psychic powers of their own, and after doing so, are known as Shamans by their fellow kin, who then lead their fellow Kroot in ancestral worship.