In Warhammer Horus Heresy, the Primarch Angron had surgical implants in his head known as the Butchers Nails. These implants were forced upon him in his youth.

In the second Horus Heresy book, 'Galaxy in Flames' it is said "Although the technology to have them taken out existed, he had never wanted them removed."

I doubt that's the exact quote and if someone has the quote I would much appreciate it. But you get the gist. They could remove them if Angron wanted.

However, later on we are given evidence to the contrary.

In the Audio Drama entitled, 'Butcher's Nails' Lorgar says to Angron,

"They cannot be removed. Not without killing you. I had no intention of trying. if it is possible for us to die, you will do so with those wretched things inside your skull."`

Also in the Lexicanum it says that, because the Butcher's Nails were hazardous to psykers, most of them tried to have them removed. But, they all died.

It seems they know what they were signing up for as Angron offered them a chance to be honourably executed by him instead, but almost all decided to risk having them removed.

So can they, or can't they be removed? Did the technology used to exist but was lost early in the Heresy? Or was Loken just wrong? Or was Lorgar wrong and Angron lied to his Psykers?

In regards to Warhammer lore I believe the saying goes, "Everything is Canon. But, not everything is true."

So what is the truth of this matter? Does anyone have any other sources that support the for or against?

  • 1
    I don't understand how Angron could have been lying to the psykers. He offered them an honourable execution instead of trying to have the nails removed - but almost all of them decided to try having the nails removed. If the idea that they can't be removed were a lie, why did they all die?
    – Steve-O
    Jul 30, 2017 at 22:16
  • 2
    That saying is most definitely true... I always thought that it was certain death to remove them. That the nails actually replace on incorporate themselves into the brain somehow. I have not read either of the books, but given the second title is Butcher's Nails I would think it would be more trustworthy as a source! Canon would suggest the most recent source is the current accepted philosophy.
    – Odin1806
    Jul 30, 2017 at 22:26

2 Answers 2


In the book "The Master Of Mankind" this is actually expanded upon in a flashback with the Emperor and a Tech Priest of Mars. I can't find the actual quote, but even the Emperor concedes that they cannot be removed without killing Angron and he is of the opinion that an Angry Angron is better than no Angron

So it's a conversation with Arkhan Land

'Can you remove it?'

'Of course' the Emperor answered ...

'Then Divine One, why would you leave it there?'

'This is why'




'They are the only thing keeping him alive' Arkhan said

.... .... ....

'A compromised Primarch is still a Primarch' The Emperor mused

It's split over 2 pages so I've trimmed some none relevant pieces

  • Thanks a bunch. If you can find the quote, I'll accept the answer. Aug 7, 2017 at 22:02

At some point following the rediscovery of Angron, Arkhan Land was brought to a secret laboratory hidden in a dormant volcano in a tundra location on Terra to aid in the Emperor's investigation of Angron's crude augmetics as the Primarch lay unconscious. Land had previous experience with the device taking over Angron's body, having seen it when investigating the Hexarchion Vaults before he ordered them sealed due to the threat the items within presented to the Machine Cult. He told the Emperor that it was called a cruciamen, but the versions he saw were more crude. The Emperor explained that the implants were not His doing and that He believed they led to the Angron's instability. He also explained that they were recreated to remove the ability to enjoy anything but anger. When asked if the Emperor could remove it, He admitted He could, but the tendrils were deep in Angron's head and spine and he was missing his limbic lobe and insular cortex. The Butcher's Nails therefore replaced part of Angron's brain, allowing him to live.

Master of Mankind (Novel) by Aaron Dembski-Bowden, Chapter Seven

Regarding the Librarians the nails did not directly kill them, instead it made them lose all control of there psychic powers. One Librarian immolated 3 squads of the 100th company when he lost controls and fired warp fire from his eyes. Throughout the legion Librarians either self com-busted or suffered from similar bouts of uncontrolled psychic eruption.

Therefore Angron had to give the Librarians a choice, either be executed in order to not bring any more risk to the Legion, or undergo an operation to remove the nails which would undoubtedly lead to there death. So it wasn't a case that they tried to have them removed, they had only 2 choices, either be killed before one of them exploded and caused irreversible damage to the legion, or cost them a battle. Or attempt to have the implants removed.

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