Cryptek

Crypteks are the Necrons' equivalent of wizards, although their powers come from an extremely advanced understanding of science, rather than magic. 'Cryptek' is actually the ancient Necrontyr word for nerd.
Like wizards nerds, they tended to isolate themselves from the affairs of their fellow Necrontyr. Most nobles are happy to leave the Crypteks to their own devices, rather than put in the effort to actually understand how any of their shit works. Like IT, Crypteks are basically allowed to mess around as they like until their boomer bosses forget to plug in the monitor again.
Those that do associate with others generally do so for loot — they join the royal court of an Overlord or Phaeron and lend their powers and advice in exchange for a first pick of the spoils of war, rare technology, or other favors. These Crypteks rarely bother with the political affairs of the noble courts, as they are too occupied with their own inter-academic rivalries and the struggles of organizing D&D groups when your character sheet needs to be engraved on a 30ft obelisk.
Disciplines

Crypteks specialize in one of several disciplines to focus their studies and gain more powerful tools.
- Harbingers of Despair or "Psychomancers" are all about manipulating minds, mostly causing fear.
- Harbingers of Destruction or "Plasmancers" shoot fire and light to wreck things. Now with their own plastic model!
- Harbingers of Eternity or "Chronomancers" play tricks with time -- speeding it up, slowing it down, shifting people into or out of phase with it, or even (in the case of Orikan the Diviner) running it backwards.
- Harbingers of the Storm or "Ethermancers" control the air and weather. In battle, they call down the lightning (ACDC optional).
- Harbingers of Transmogrification or "Geomancers" are rather like alchemists -- they can transmute matter from one form into another, or animate it temporarily (which is good for causing earthquakes). Somehow they are able to rock your armor off, AWWW YEAH!!!!
- Astromancers read the patterns and movement of the stars to predict the future. Yeah, they're basically astrologists.
- Biomancers are the guys who do experiments on organic races.
- Technomandrites are the most advanced and knowledgeable of the Crypteks, and designed practically all of the Necron tech that's currently in use. They were banished by the Silent King because he feared their power, but they were released from exile by special anti-Chaos protocols after the opening of the Great Rift.
There are other disciplines, but the first five are the only ones who go to battle on a regular basis.
All used to be in harmony, and then the 7th struck. Taking away this glorious collection of stuff and gear we were introduced to the HQ that (for some fun reason) costs the same as a 5th lord with a res orb. And fun fact: it is giving them +1 to their Reanimation. Now that would not be so bad were it not for the T4 and the 4+ save...
Still as an HQ if you didn't have the points to make a reclamation legion you did good to take this guy and just simply stick him to the most important unit (that would be Immortals or a huge group of Warriors) to keep them alive. Could also take a little thing that gives a 5++ against shooting.
The modern Cryptek family
9th Edition came in looking to step back the horrible mistake of removing these specializations, as the Indomitus boxed set is including a Plasmancer as a new model and the Cryptek with Canoptek Cloak has been renamed Technomancer. HUZZAH! Our hopes were high that this meant the other disciplines were also gaining new models. And our prayers were promptly answered when the Psychomancer and Chronomancer have joined the plastic ranks of the New-crons, looking baller as fuck.
As of now, only 4 disciplines have their own individual models and rules :
Technomancer

a.k.a Cryptek Classic™, you take him in order to buff your Canoptek units, which he can do seamlessly. He also has access to a number of stratagems specific to them.
Plasmancer

Initially introduced in the Indomitus Box, plasmancers are the subclass that delves in high-octane plasma. Officially the Harbingers of Destruction, they are masters of raw energy and can shoot devastating blasts of furious energy and pulses of light that illuminate the entire battlefield from their Eldritch Lances in battle. Their gaze of flickering witch-fire falters the onset of even the bravest attacker.
This ominous title is well earned, as it happens. A Plasmancer is also a master in the art of weaponising the hypertechnology of the Necrons, and the plasmic lance its bears – equally deadly at range as it is in melee – is a fine example of its skills given form. Floaty and frail-looking? Yes. Super deadly at every distance? Also yes.
Hard crunch wise, the Plasmancer's main ability is basically a smite, striking at the closest enemy unit within 18", throwing 3D6 and inflicting 4 mortal wound for each roll of a 4+. In addition to this, and harder to make use of without throwing him in harm's way, his Lightning Aura deals 1 mortal wound to every enemy unit within 6" on a roll of a 6 (!!) at the start of the fight phase. So don't lean on that too hard.
Chronomancer

Chronomancers are the sub-class that likes to fuck around with time for work and pleasure. Officially the Harbingers of Eternity, they are pretty much exactly what you'd expect. Guys who mess around with the flow of time in the battlefield to give their metallic buddies an advantage over their fleshy opponents. Doing stuff like slowing down incoming fire from the enemy so their own troops can just stroll past without a scratch.
In terms of what we know of the actual crunch at the moment, the Chronometron piece of equipment has been made their main gimmick ability. With it allowing you to select a friendly unit during your command phase to reroll charge rolls and grant it a 5+ invul phase.
Psychomancer

But that won't save you from the screaming skull of weaponized death coming at you.
Psychomancers are the subclass that prefers to mindbreak their opponents on the battlefield, mainly sowing the emotion of fear to reap a toll from the enemy. Officially the Harbingers of Despair, they are sadists crazy enough to use tech that channels the Nightbringer, using that visage of dread and death and sharing it around with anyone who may or may not be staring at them funny.
Crunch wise, this means they have the Nightmare Shroud as an aura, making any unit within 6 inches of them subtract 1 from their Leadership as well as from their Combat Attrition tests.
Famous Crypteks
- Orikan the Diviner, an astromancer with some expertise in chronomancy.
- Illuminor Szeras, a spider-bodied plasmancer who has taken up vivisection as a hobby.
- Zaa of Tomorrow, astromancer and faithful sidekick.