The Oathsworn
Battle Cry Strength Through Purity
Number IX
Successor Chapters Is this a thing?
Primarch Faustus
Homeworld Luna
Specialty Gene-smiths and overwhelming numbers
Allegiance Fallen Imperium of Man
Colours White.

The Oathsworn are a Loyalist Legion in the Imperium Asunder.


Summary of Legion IXEdit

Numeration: The IX Legion

Primogenitor: Faustus

Cognomen (Prior): None

Observed Strategic Tendencies: Gene-purity, Mass Astarte Actions, Gene-Tech

Noteworthy Domains: Luna,

Allegiance: Imperium

Assorted Fluff yet to be properly worked throughEdit

+++ Geneseed +++

The Geneseed is remarkably pure, even 10,000 years after the heresy none other takes so easily to potential aspirants. Likewise despite the loss of their genebanks they have been able to slowly rebuild, a feat unmatched by any other legion.

Likewise, the Oathsworn have displayed a genetic disposition less compatible with chaos taint.

Common Traits: +

Faustus did all the regular primarch stuff, but like Ferrus, Vulkan and Perturabo he spent a lot of time on these side projects that changed the war. Where Ferrus basically invented all the various Terminator armors and Pertt made the best war machines, Faustus revolutionised medicine and modern science. I'd be a fan of larger legions for other legions too, at least the ones close to Faustus or have large Oathsworn detachments, to represent the discoveries he's made. It's been mentioned the Oathsworn have a couple things going for them as well for their activities. For one, his boys are basically chapter masters as we know them in 40k with their own mini fleets and recruiting bases. Then you add in the adoptive sons of that fall under other legions, who they probably get a lot if love from pre censure because of how much they help.

Second you have the mini detachments that both obscure their numbers while vastly increasing their rep with the Imperium. Pretty much every fleet or rogue trader of note have a Oathsworn present for contact with new worlds to help catalogue stuff and send up data as well as fill honor guard roles. Whenever a new world is found, they send out a ground crew with Oathsworn to do all the inspections for hostility/hability. Plus first contact goes smoother when you have a giant benevolent war god who is immune to small arms fire but brings the cure to space cancer. Oathsworn are boring and vanilla compared to others Legiones and their glory, but when humans think Astartes they think Oathsworn.

Third, the lesser known thing and part of why the Oathsworn don't have as many glories are their destroyer corp. Others have them do rad stuff and phosphex. Oathsworn reduced worlds to sludge and rock. None loved humanity more. None hated the alien more. Their biophages are the stuff of nightmare, and helped give the warmaster work up a fear about the Oathsworn.

The last and worst part was their independence. Even with working on the front, Faustus got a lot of leeway to spend time with his projects. This gave his commanders a lot of time to do shady stuff, which let some go off the deep end with their own experiments. The Warmaster had plenty of things to gather as evidence of OS going rogue, and we might even have past censures of small warbands. The Oathsworn are beloved by the people, but no one really likes or trusts Faustus.

On a side note, I imagine Luna gene-wright culture probably continues in the legion as a secretive order or cult to outsiders like the Mechanicus or Dark Angel circles. A notable aspect of their inner orders is that everyone has a role or archetype they are reborn as Astartes to fill. You're the Hunter, the General n ect. The cults helped resist REDACTED spies during the heresy by being insular and hard to infiltrate, but looked shady and religious as all hell to fellow legiones.

Faustus didn't do personal combat too much himself I bet, but likely had a dizzying array of equipment meant for science but repurposed for war. A narthecium that gives him fleshbane and armorbane with applied potions, a couple destroyer plague grenade gun, and other wonderful. He'd be a good combatant if he was, wel, a good fighter. Compared to mortals he's a god, but against any primarch other than the warmaster he'd get his ass beat. Definitely a buff primarch if this was a Horus Heresy FW model.



Legion TacticsEdit

The size of their legion prevented coherent supply lines in the later end of the Great Crusade, which was forcing chances to their organisation and doctrine. However for the majority of the crusade they were considered the 'standard', having a nicely balanced make up of their battalions, favouring nothing in particular allowing them to adapt easily to their opponents strengths and weaknesses.

Legion OrganizationEdit

Legion Organisation.

Special FormationsEdit

>Silent Knights The culmination of Faustus' experimentation with Nulls, the Silent Knights are able to project a directional null aura. At the Siege of Terra they were reported to weild psychokinetic blades that could drain the life from psykers and daemons, as well as supposedly being armed with a Speculum Anima-like device. Unfortunately the secret to their creation was lost with Faustus, and the so-called Silent Knights of later days are less powerful and far harder to make.

>Genomancer Cadre Of perhaps kindred spirit to the technomancers of the Behemoth Guard, the Genomancers take to the field of battle with their biological creations. These range from gene-bulked servitors to cy-carnivora, to far more esoteric beasts. According to legend, these included dragons deployed to fight daemons over Terra, but this is considered doubtful.

>Huskarls Such was the gene mastery of the Oathsworn that they could improve some on Astartes design. Essentially lesser Custodes, these guys get extra bling.

>Berserkers Thunder Warriors, basically designed as a disposable shock troop. A number underwent treatment similar to the Eversor Assassins to maximize their lethality.

Legion RelationshipsEdit

Legion HistoryEdit

Great CrusadeEdit

1. something something 2. something else 3. Faustus is bad leader, likes to be in the lab more 4. Warmaster grows uncomfortable with huge numbers 5. warmaster sets up them as patsies 6. Oathsworn called out as renegades 7. X. Y, Z called in to purge them 8. They fight above luna, recalling their numbers from across the stars. 9. Long battles, the loyalists sent in all die off, once gone the Warmaster summons great demons to fill the gap they leave 10. Faustus releasing his pet projects to combat them (Dragons, Bio-Warriors, Obliterator EQ) 11. Seeing inevitable defeat, Faustus launches Luna into the face of Terra itself 12. Something stops it...

The Red Road to TerraEdit

The Eastern ImperiumEdit

Creates the post of Gene-Lord, who takes a seat in the Imperial Senate, the First Gene-Lord Bastion even attends the Council of Titans.



Gene Lord Bastion, of the Oathsworn.Edit

Once a lowly Breacher Squad Sergeant destined for nothing more than a death on a forgotten battlefield amongst the stars, Bastion became a symbol of defiance and determination not only to the surviving Oathsworn, but to the many worlds that aligned themselves with the legion in what they saw as a brutal attack brought on by the corrupt Imperium. Bastion was in charge of boarding and counter boarding actions aboard his section of The Dauntless. When the fleet was attacked by an armada three times its size made up of Marines and the Imperial Navy, Sergeant Bastion survived by having been aboard a War Hawks ship when the Frigate was destroyed under the weight of the combined fire.

With brothers being slaughtered and the Oathsworn flotilla being slowly destroyed in the void, picked apart by the Warhawks, Bastion lost himself to insanity and rage. Taking his strike team on a rampage, he sabotaged the life support by implanting a biophage into the network only the Oathsworn could have survived before setting upon a massacre of the survivors. With the ship theirs, Bastions men used the powerful guns to turn the battle and later reave a bloody path through the void and warp on a race to Luna.

There against all odds the Sergeant survived once more, and managed to collect the largest gathering of survivors from the Oathsworn, some 200 marines. Later at the gathering of the Primarchs the Sergeant was rebuffed for his efforts and attendance, only for the man to declare himself the Gene Lord of the Oathsworn and the primarchs all manner of foul titles for their involvement in the censure and inability to protect Terra and the Emperor. Where had they been when Faustys and the Oathsworn gave everything to hold the line from the unending tides of Daemons? Where were they when Faustis and the legion sacrificed 99% of their legion to buy time for everyone to get off Terra? Where were they when Faustus, brightest and smartest of them all died?

>Johannes Hoenheim, the ChiurgeonEdit

One of Faustus' brightest, Hoenheim was there during the siege of Luna, one of the few Oathsworn to escape. Entrusted with preserving as much of the Oathsworn's work as possible, Hoenheim escaped with Knights Exemplar even as Luna plummeted towards Terra. Hoenheim is a complicated man. On the one hand, he seeks to preserve the legacy of his gene-father, wandering from court to court in the East instructing and researching as the opportunity presents itself. At times he even creates stunning works if genomancy. Despite this, Hoenheim is haunted by his memories of Luna, and, in particular, he cannot forgive the Judgement Bringers or the Paladins of Kor. When his humors swing towards the cholera, Hoenheim will vanish, only later to appear reaving the Protectorate or attacking the Judgement Bringers. It is suspected, but never proven, that these raids on the Protectorate are sponsored by various other states. For Hoenheim's part, he cares little as long as he is able to extract some quantum of solace from his revenge. Towards this end, Hoenheim went on a rampage throughout Paladin space during the Paladin's war with the Angels.


The tank that would later become infamous post-Heresy originally served with the Second Sons as a standard Predator. Third chapter, second battalion, sixth company. It survived for almost a hundred years in continuous service during the Crusade before the outbreak of the Heresy, and was deployed on Armageddon at the time. It had seen numerous modifications over the course of it's long service, including a larger bore main gun to fire specialized radium and phosphex shells and significantly increased armor. It had also already received numerous appellations from it's crews, some having died while the tank stayed in service, the most famous being the large image of a snarling xenos on the gun and the accompanying low gothic scrawl "WARBEAST". At Armageddon Warbeast and the rest of it's battalion were deployed in the central marshland, one of the most contested regions of the war torn planet. By the end of the conflict, the entire rest of it's company had been wiped out and Warbeast was operating alone with no contact with command. More than once the Predator was bogged down and almost overwhelmed by orks, but every time it held out. Eventually, when the Second Sons decimated Armageddon, Warbeast and her crew fled with the Undying Scions back to Terra.

On Terra the Predator continued service on the front line, with it's legion markings removed, eventually being overwhelmed and lost during a traitor attack. The tank was then recovered by a loyalist counter attack, still mostly intact but the crew dead to the last. It was evacuated from the planet by a group of loyalist black-shields.

It has since served nearly ten millennia, fighting doggedly with the descendants of the Blackshields that recovered her. Hundreds of crews dead or moved on, thousands of battles fought, and uncountable modifications, repairs, and new designs scratched or painted onto her hull. Warbeast fights on, an enduring icon of the loyalists from the traitor legions.