This is what happens when the Inquisition fails to successfully locate and contain a really powerful Psyker. Rogue Psykers are Human Psykers that now belong to the Forces of Chaos. Many have eluded either the Inquisition's Ordo Hereticus or the Adeptus Astra Telepathica's League of Blackships and have become tainted by the Gods of Chaos, a process which drives the psyker completely Emperor Palpatine-levels of bonkers. Their powers are completely out of control, capable of causing mass destruction but also making the psyker himself prone to possession by Daemons. The Lost and the Damned makes use of these to combat enemy psykers and unleashing a torrent of mind bullets at the designated direction.
In the rare chance that a Rogue Psyker gets captured by the Inquisition again and somehow becomes compliant to Inquisitorial rule, then he/she would become a Bound Psyker. The Inquisition uses these redeemed heretics as living lightning bolts to purge the enemies of man.
They appear in the Space Marine Video Game and are notorious for being ludicrously durable for a such a feeble person and spamming unrelenting mind bullets at you. Seriously they can take a fucking Lascannon to the face! and survive!?
Rogue Psykers are moderately expensive and you are able to buy up to 5 level 1 psykers as an HQ choice, which on the surface sounds great, they have a special set of powers, all of which are fairly decent. As they are harnessing the raw power of the warp, and aren’t nearly as resistant to the energies as a well trained psyker, if they’re ever forced to suffer a wound from a Perils test, they are instead possessed, get an enhanced stat-line, but are no longer a psyker.
Their psychic powers are:
- Creeping Terror – forces an enemy unit within 12″ to only snap-fire and have Initiative 1, though units that are fearless are unaffected and units with ATSKNF or Stubborn are allowed to take a LD test to ignore the results.
- Warp Flux – A short range (12″) witchfire with a S7 haywire blast, not too shabby.
- Unnatural Vigour – Probably the most useful, it targets any friendly unit within 12″ and they gain both Fleet and Crusader, which combined with Covenant of Khorne and some combat drug injectors can turn an unruly mob into a deadly horde in melee.
The Oof! (8th & 9th Edition Changes)
So, the big change in 8th was the loss of access to a bunch of powers that were available in 7th. Rogue Psykers lost the enhanced statline from Perils, which is now exclusive to Malefic Lords. The powers changed a bit to compensate for the loss of USRs from 7th. Creeping Terror debuffs leadership, Warp Flux is a modified Smite and Unnatural Vigour buffs strength and attacks. The higher warp charge cost of Unnatural Virgour made this power a prime candidate for use by Rogue Psyker covens as they could trade mortal wounds to get 3D6 for a psychic test.
We say made because 9th edition purged all the psychic powers for Renegades and Heretics. The only power this unit has access to is Smite so Rogue Psyker covens are now not worth taking unless you took allies with no psykers.