The Imperium measures and records the psionic activity and power level of psychic individuals through a rating system called The Assignment. Comprised of a twenty-four point scale, The Assignment simplifies the comparison of psykers to aid Imperial authorities in recognizing possible threats.
Beings which utilize psychic powers, or psykers, exist within many of the races residing within the galaxy. Human psykers, all Eldar, Ork Weirdboyz, Space Marine Librarians and Chaos Sorcerers all fall into this catagory. Beings such as Daemons of the Warp are made of purely psychic energies. There are races like the Tau, which are devoid of psykers or psychic powers. There are even beings which could be called anti-psykers, Human Blanks or Pariahs, Necron Pariahs, and Culexus Temple assassins are all examples of such beings. Due to their use in the armies of Man and their relative abundance in the Imperium's enemies, the Imperium has devised a way to clasify all psykers it may come across.
The average Homo Sapiens Imperial is judged to have an Assignment rating of Rho or Pi. These individuals cannot consciously or subconsciously draw power from the Immaterium and are not able to become possessed without outside psychic influence. As the vast majority of Mankind falls into this Assignment level, the common Imperial citizen poses little psychic security threat.
Nevertheless, uncommon individuals are birthed every day with Assignment ratings exceeding Pi. By Imperial Edict, these men and women are to be discovered and brought to the attention of the Inquisition to protect against harmful psychic events. With the multitude of threats besieging the Imperium, however, it is only truly practical to investigate those suspected of Iota level talent or greater.
The Imperial Assignment: Positive Psionic Levels
In ascending order:
- Rho // Pi
- No manifestation of psychic talent (common human being).
- Omicron // Xi // Nu // Mu // Lambda // Kappa
- Unconscious and minor level of psionic brain activity. Such low levels of talent only manifest in high-stress experiences and remain beyond the control of the individual. Phenomenon commonly explained as "good luck" or "fluke" occurrences.
- Iota // Theta // Eta
- Conscious and moderate level of psionic talent. As the individual is able to control abilities with effort, subjects of Iota level and higher are true psykers and under the jurisdiction of the Inquisition and Adeptus Astra Telepathica.
- Zeta // Epsilon
- Very high level of mental psychic activity. Manifesting early, these levels of talent (and those above) require the immediate attention of Imperial authorities and represent a true security threat.
- Delta // Gamma
- Occurring in approximately one-per-billion human births, Delta and Gamma level psykers exhibit extreme levels of psionic ability. Unless discovered quickly, death or possession are common results of the untrained mind being unable to handle this level of mental energy.
- Beta // Alpha
- Exceedingly rare and dangerous. Mainstream Medicae Imperialis discussion agrees that current human beings do not possess the necessary evolutionary development to contain Beta and Alpha levels of psionic talent. As such, the great majority of those discovered at this Assignment rating usually suffer from mental instability.
- In the rarest of all cases, the twenty-four point scale of the Assignment does not adequately characterize a being of indescribable ability. Such individuals, for all intents and purposes, pass beyond the scale entirely. These subjects are known as Alpha-Plus psykers.
- Uncontained, Alpha-Plus psykers represent an immediate and catastrophic threat to the Imperium. In theory, there is nothing that a trained Alpha-Plus psyker cannot accomplish through force of will; from snapping a Titan in half to summoning a legion of Greater Daemons. Representing such a great danger, the Inquisition usually executes Alpha-Plus psykers on sight unless the possibility for capture is nearly assured.
The Imperial Assignment: Negative Psionic Levels
Extending below Rho, the twenty-four point Assignment scale classifies specific levels of psychic-inactivity. While not as serious a threat as unchecked psykers, these rare individuals exhibit calming and negative effects upon the Warp.
- Sigma // Tau
- Psionically-dense individuals who are oblivious to warp fluctuations and manifestations of psychic talent.
- Upsilon // Phi // Chi // Psi
- Subjects with varying degrees of immunity to psyker powers.
- Usually referred to as Untouchables, Pariahs, or Blanks. These individuals are so inert in the Warp as to actually exhibit negative psychic influence upon others. Primarily manifested as a small region of "blankness" surrounding the individual, it is impossible for psychic powers or warp creatures to penetrate this space.
- Those at an Omega level of psi-negativity can easily be distinguished by others, as Imperial science has shown the dead-area surrounding the subject interferes with natural electrical-mental functions. This often results in irrational fear and loathing of the individual for normal humans. For psykers, however, Omega level persons are physically and mentally painful to be near.