Psychic Disciplines

"There are different kinds of darkness,” Rhys said. I kept my eyes shut. “There is the darkness that frightens, the darkness that soothes, the darkness that is restful.” I pictured each. “There is the darkness of lovers, and the darkness of assassins. It becomes what the bearer wishes it to be, needs it to be. It is not wholly bad or good."

– Sarah J. Maas, A Court of Mist and Fury

The Basics

There are five "basic" psychic disciplines in the grim darkness of the future. Generally speaking psykers prefer to focus on one discipline if they seek more power, but doing so runs the risk of changing their mindset, as connection between psyker's mind and the Warp goes two ways, and if one is to use his mind to alter the Warp, said connection would alter the psyker's mind. Some psykers fight this, some don't, and most don't live long enough for this to take effect.

• Biomancy is about flesh/life force manipulation and shooting lightning, somehow (probably bioelectricity, but depending on your interpretation, either pyromancy or telekinesis fits this power better). Old and powerful biomancers tend to become quite sick fucks, building cruel and sadistic tendencies over time.
• Divination is about predicting and tweaking the future. Old and powerful diviners are known to be extremely nerdy, hoarding massive amounts of knowledge about deciphering visions and omens and general theory of the Warp, but this often comes at the price of constant melancholia and depression, as they realize how much of a puppets in the hand of Fate they are. Unless that diviner is Ahriman, who decided to skullfuck Fate and be the one in charge of his own destiny (though even he went though an "I'm just a puppet" emo-phase before it).
• Pyromancy is about conjuring and throwing fire at people. It comes to no surprise to anyone that pyromancers that happen to live long enough without blowing themselves up often to grow into aggressive pyromaniac hotheads that tend to solve all problems by SCOURGE AND PURGE.
• Telepathy is pretty much self-explanatory - reading and translating minds. Mind control and mind rape goes there, as well as invisibility, even though this power renders you invisible to things without minds. In terms of long-term personality changes Telepaths draw the absolutely shortest straw, as over time they "pick up" bits and pieces of personalities of people they mindraped, risking to lose their original selves eventually, and even if they have the will to resist it, they inevitably grow into absolute misanthropes due to knowing too well what disgusting things people around them think about all the time.
• Telekinesis is also obvious - moving things with a mind. Here also goes psychic shields and somehow dimensional gates. Not much known about how it affects psyker's psyche - old telekines are known to being quite stoic, even stubborn but many unspecialized psykers that manged to survive for long without losing their minds also tend move towards this archetype, so it's debatable whether it's discipline effect or a simple natural selection.

Advanced

• Daemonology is a discipline notorious for being much more difficult to learn and dangerous to use (as anything that directly deals with chaos daemons carries the possibility of the psyker's head exploding into a warp portal). It's split into two sub-disciplines - Malefic is about summoning daemons and using their power, and Sanctic is about banishing them and killing things with the refined unshaped Warp energy. Generally speaking most dedicated daemonologists do not live long enough to experience any personality-changing effects of their discipline, and those that do are either extensively indoctrinated during their training in order to use it safely (Grey Knights) or are already Chaos-corrupted and affected by daemonic pacts (Chaos sorcerers and rogue psykers).

Specialized Disciplines

Chaos

Ahzek Ahriman, THE go-to guy to bolt your enemy to fried crisp.

Chaos psykers and daemons use their own specific disciplines, dedicated to one of the three gods who don't hate sorcery:

• Tzeentch is mostly about mutation, subjugation, and manipulation of the warp itself. Tzeentchian powers typically revolve around controlling the energies of the warp itself to damage foes (like Doombolts), mind-reading and controlling people, and manipulating reality to either open warp rifts or mutate their opponents into those-which-shall-not-be-named.
• Nurgle is like a twisted version of Biomancy, focusing on the psyker spreading the gifts of Papa Nurgle by polluting their surrounding area with his many plagues and contagions, causing most people to succumb and die within minutes. The "beneficial" parts of these are mostly related to raising a recipient's endurance, as the many blessings of Nurgle can do anything from mending grievous wounds in an instant, to granting them inhuman resistance to damage.
• Slaanesh tends to be the trickiest, focusing on illusions, and manipulating their targets' senses to either control them or drive them into the throes of insanity (Which can either be good or bad depending on the power involved). Slaaneshi powers are a bit similar to Tzeentchian ones, although are focused more around manipulating the physical and mental characteristics of people to the extreme (something they have control over), rather than their fates and surrounding reality (which people typically do not).
• Khorne views psychic powers as cowards' tools, and so generally gives his followers an anti-psychic boon, and his mortal champion Kharn has immunity to ALL psychic powers.

Eldar

Well, they get their dead fighting again by singing the Warp into shapes.

The Eldar have developed four disciplines of their own; the first two use runes as proxies to manifest psychic powers, so they don't get mind fucked by Slaaneshi daemons the moment they surge in the warp for the power, and they created two disciplines to utilize those runes:

• Runes of Fate Used by Farseers is kind of like Telepathy and Divination mixed together and shaken a bit - same kind of future telling and mindrape in a slightly different form. Except for Eldritch Storm, which looks like it was pulled form the Sanctic Daemonology.
• Runes of Battle Used by Warlocks and Spiritseers. Features a set of powers that can be used to buff allies or debuff opponents, most of which don't fit into any of the basic disciplines.
• Harlequin Shadowseers also use their own discipline called Phantasmancy, which is basically Telepathy on an acid trip, as the psyker channels his own killer-clown kind of batshit insanity into people, and polishes it out with hallucinogen grenades thrown on the top.
• Eldar Corsairs, being cool space pirates, do not utilize rune stones, and channel psychic powers the old way, at a higher risk of being raped by daemons. Their old-school techniques allow them to use pre-fall magic called Aetheromancy, designed to utilize the Webway (similarly to how Sanctic Daemonologists utilize the Warp), so they can project a guidance map, teleport their allies through it, and create rifts that suck their enemies into it.
• Ynnari bring with them the new Revenant discipline which looks suspiciously like Necromancy but isn't we swear.

Orks

Ork Weirdboyz have their own discipline, that runs on Waaagh! energy rather than the Warp, and don't have access to other disciplines. Surprisingly, Waaagh! powers are quite powerful and some of them are tricky, although they are mostly focused on pumping the boyz around the Weirdboy with buffs, getting them closer to enemies or killing shit with green lightning.

Tyranids

Similarily, Tyranids, whose psychic powers also run on a collective psychic field, have a specific discipline, which is Telepathy with a bit of Biomancy and the odd Zoanthrope mind bullet power thrown in.

SPESS MAHREENS

A fine demonstration of fulmination. Pity its target.

Spaсe Marine librarians have developed not one but FOUR special disciplines, which Chaos Sorcerers rename because they have to be different:

• Technomancy/Heretech Telepathy/biomancy for machine spirits rather than living beings, for those who prefer the company of machines or like to wreck enemy ones.
• Fulmination/Ectomancy I have the power! A discipline that throws away all that life force and biochemistry shit and focuses solely on the lightning. All the lightning!
• Geokinesis/Geomortis If you ever wanted to be an earthbender this is the discipline for you. Among other things it allows you to move buildings, hills and forests around.
• Librarius/Sinistrum Very Eldar-runes-like telepathy/divination based discipline with trickery thrown in.

Space Wolf Rune Priests use a discipline called Tempestus (although they refuse to admit it's a psychic discipline at all, since they're hypocrite assholes) - it involves powers that mostly revolve around ice, earth, and storms. It looks like it utilizes a psychic ice effect, which is a common side effect of manifesting powerful non-pyromancy powers, and then they mix that with a bit of Telekinesis to spin that ice around or shape it into giant killer wolves that eat you alive.

Blood Angels and their successors claim to have their own discipline called Sanguine but it's really just a bunch of Biomancy, Telekinesiss and Telepathy powers thrown together and given fancy names. Their buffing spells have a tendency to affect allies, rather than just the psykers at the cost of sheer power, possibly due to the selfless nature of their chapter. Then there's the Blood Lance - which is just the entirety of their psychosis bottled into one power, with all the heat and fury of the Black Rage with the color of the Red Thirst.

Dark Angels utilize the Interromancy discipline, which is a specialized variant of the Telepathy discipline, originally designed to interrogate Fallen FOUL TRAITORS WHO ARE NOT IN ANY WAY CONNECTED TO THE FIRST LEGION. It may lack some of the most bullshit OP powers of true Telepathy, but has a strong combination of buffs and debuffs and the latter have a chance to permanently cripple their targets, especially if they are weak-willed.