Polonius wrote:
I think grimskul nailed it. Between being told not to, and the results of those that did, the risks seem high.

It’s also a skill that requires time and energy to learn. There are plenty of skills people could learn that would make them more effective, but we choose not to devote the time to learning them.

 Lord Clinto wrote:
There's also the fact that some Primarchs were just blunts too

"Blunts"
Khan: I think it was his friend Magnus that said he had no psychic power whatsoever.
Russ: No power that we were aware of.
Gulliman: Super-OCD?
Manus: None that we know of.
Fulgrim: None that we know of, until he became a Daemon Primarch.
The Lion: None that we know of.
Perturabo: None that we know of.
Angron: None that we know of; Butcher's Nails.
Dorn: ?
Vulkan: ?
Horus: None that we know of before Falling.

"Psykers"
Lorgar
Magnus
Sanguinius: future sight / precognition
Corax: obfuscation.
Mortarion: Had a minor psyker gift but refused to utilize it. / passionately hated psykers. And even though he is now a Daemon Primarch still is basically a novice psyker.

"Maybe's"
Alpharius/Omegon: twin bond? (if that can be called psychic).
Curze: death premonition?

Nurglitch wrote:
In The First Heretic Lorgar comments that his psychic gift is unreliable, and it's kind of the climax of the novel where he decides that he's going to rely on it anyways. He's also known as the weakling Primarch.

 Duskweaver wrote:
According to Slave of Nuceria, pre-Nails Angron had psychic healing powers. More specifically, the ablity to relieve the pain of others by taking it upon himself.

I think it is misleading to think of any primarch as being 'not a psyker'. They were all sorcerous creations, essentially artificial daemon princes poured into genetically enhanced host bodies.

Nurglitch wrote:

 Duskweaver wrote:
According to Slave of Nuceria, pre-Nails Angron had psychic healing powers. More specifically, the ablity to relieve the pain of others by taking it upon himself.

I think it is misleading to think of any primarch as being 'not a psyker'. They were all sorcerous creations, essentially artificial daemon princes poured into genetically enhanced host bodies.

You can have non-psyker daemons.

pm713 wrote:

Nurglitch wrote:
In The First Heretic Lorgar comments that his psychic gift is unreliable, and it's kind of the climax of the novel where he decides that he's going to rely on it anyways. He's also known as the weakling Primarch.

In fairness to him I believe he did get better as the Heresy progressed and was decent once he went demon. Until Corax went demonic and kicked his ass. Again.

pm713 wrote:
Why would Lorgar have an abnormal psychic potential? I see why Magnus does but not Lorgar.

mrFickle wrote:
I’m isn’t the idea that all the primarchs have a strong warp presence but for many of them it works on a level of intuition rather than controllable power, like Magnus. They all have an image defender against psychic attacks and can sense psykers and have an intuition about the warp and a connection to each other and the emperor but for most it ends there. Although that’s pretty solid

 Void__Dragon wrote:

pm713 wrote:
Why would Lorgar have an abnormal psychic potential? I see why Magnus does but not Lorgar.

This is kind of a ridiculous question on par with "Why would Yao Ming be abnormally tall? I could see why Shaq is, but not Yao Ming."

Some people are more talented than others at certain things. You might as well ask why Perturabo would be abnormally intelligent compared to his brothers (he was, arguably the most intelligent of all of them with a superhumanly intuitive understanding of basically everything).

If Magnus is the Michael Jordan of psychic potential among the Primarchs, Lorgar is simply the Lebron James.

Nurglitch wrote:
You can have non-psyker daemons.

 Void__Dragon wrote:

mrFickle wrote:
I’m isn’t the idea that all the primarchs have a strong warp presence but for many of them it works on a level of intuition rather than controllable power, like Magnus. They all have an image defender against psychic attacks and can sense psykers and have an intuition about the warp and a connection to each other and the emperor but for most it ends there. Although that’s pretty solid

This actually isn't true and is a widely-parroted misconception.

With the exception of Leman Russ the Primarchs are NOT innately more resistant to psychic powers. Their vastly superhuman durability and ability to heal much more grievous wounds than basically any other organism in the galaxy helps them survive psychic assaults and against most psykers they are so quick on the draw they can kill them before they can do any damage sure, but when actually forced to endure them?

Leman Russ notes that he seems to have an innate resistance to psychic powers that allowed him to survive Magnus' assault which would have grievously wounded or killed his other brothers.

Lorgar is able to easily telepathically compel Horus in Aurelian, and in Betrayer using Enuncia broke Angron's nose and sent him flying as a mere demonstration.

Malcador was able to knock out Angron with a touch, and at one point psychically strangled Horus who was helpless to resist it, with Jaghatai Khan literally begging him not to kill his brother.

Now, so far I've only brought up the three most powerful humanish psykers short of the Emperor himself true, but most damningly, in Know No Fear Kor Phaeron was able to get a psychic barrage off on Guilliman that devastated him and brought him down, with Guilliman only prevailing because Kor Phaeron tried to corrupt Guilliman with the athame rather than just finish him off.

A lot of the Primarchs had psychic abilities yeah, but psychic resistance doesn't seem to be one of them.

pm713 wrote:

People aren't designed at a genetic level.

 Void__Dragon wrote:

Nurglitch wrote:

They all have Adamantium Will, a rule for psychic resistance, in the HH game.

Ah, if I'm honest with you I don't really care tbh lol. The HH game also has Lion El'Jonson being physically stronger than Leman Russ (who was explicitly stronger, the Lion being the faster of the two).

Game mechanics don't equate to fluff. The latter takes precedence on this board.

Nurglitch wrote:

All the game mechanics are is fluff.

locarno24 wrote:
Pariahs can burn out and cease to be pariahs, and ultimately become mutated or possessed. It happens to Frauka, Ravenor's untouchable, to a Sister of Silence (who ends up a mutated spawn) in the Horus Heresy series and even to a Culexus in Daemonifuge