Alpharius Omegon

Overview

The secretive twin Primarchs of the XX Legion who presented themselves as a single being. Their true loyalties and goals during and after the Heresy remain uncertain.

They led the Alpha Legion, masters of infiltration, sabotage and deception. During the Heresy, they joined Horus but appear to have had their own agenda, influenced by a secret alliance with the Cabal, a xenos group that hoped to end Chaos. Their true motives remain unknown. Alpharius Omegon were twin primarchs who led the Alpha Legion together while pretending to be a single primarch. They were the last primarchs to be found and the masters of deception, infiltration and disinformation. Their reasons for joining Horus remain deliberately unclear, linked to the Cabal and its xenos-driven prophecy. Even their deaths are disputed, and the Legion's secrecy makes the truth nearly impossible to learn.

Origins

The last Primarchs to be rediscovered; the accounts of their discovery conflict, which suits the Legion's love of misdirection.

Their discovery remains one of the Imperium's mysteries. The commonly told version says Horus rediscovered Alpharius and sent him to the Emperor, who secretly gave both twins command of the Legion; a rival court rumour claims the Luna Wolves stumbled on him by accident as the leader of a human star confederation. Either way, they led the XX Legion through its final years of the Great Crusade.

Like the other Primarchs, the twins were taken from the Emperor's gene-laboratory beneath the Himalazian mountains and scattered through the warp. Their link with the Cabal began through John Grammaticus. He was a Perpetual, a psyker who had lived for thousands of years, and he had met the Emperor in person during the Unification Wars. The Cabal showed the Legion two possible futures. In the second, the Alpha Legion sided with Horus and Horus won. After killing the Emperor he came to his senses, and in his self-loathing he wiped out the human race within a century. That would also starve the Chaos Gods, which depend on humanity's psychic presence in the warp. The twins chose to follow this terrible path.

Key events

1. Was the last Primarch to be reunited with the Emperor. Horus was closely involved, and the existence of his twin, Omegon, was kept secret from almost everyone.
2. Sided with Horus while claiming to act on information from the Cabal, an alien group seeking humanity's sacrifice.
3. Executed endless deceptions throughout the Heresy, including an attempt on Guilliman's life by legionaries disguised as Ultramarines.
4. One Alpharius is shown being killed by Rogal Dorn at Pythos. Older lore says Guilliman killed Alpharius at Eskrador.
5. After the burning of Prospero, ambushed Leman Russ's battered Space Wolves fleet at the Alaxxes Nebula.

Their Heresy record is deliberately contradictory. After Isstvan V, Alpha Legion agents surgically disguised as dead Raven Guard joined Corax's Legion on Deliverance. They waited for his accelerated gene-seed breakthrough while stirring up the old tech-guilds of Kiavahr. At Chondax they were supposed to win the White Scars over to Horus. Instead they blockaded the Scars and provoked them. Omegon then sent Sheed Ranko's Effrit Stealth Squad on a suicide mission to destroy Tenebrae 9-50, a xenos pylon array that had been blocking warp communications. The Khan's astropaths then received Dorn's call to Terra, so the Alpha Legion effectively ensured that the White Scars joined the loyalists. Mortarion noticed the pattern and raised it with Horus, who did little about it.

Survivors from the Shattered Legions aboard the warship Sisypheum, chiefly the Raven Guard Nykona Sharrowkyn, later testified that a Primarch, probably Alpharius, had disguised himself as the Iron Hands warleader Shadrak Meduson. Using their ship to hunt loyalist elements inside his own Legion, he led them to a secret facility called Lerna 2-12, and they discovered the deception only as they escaped. The Legion's network of operatives and bondservants also allowed it to move men and materiel between sectors during the Heresy, even within the Sol System.

Battles & campaigns

• Isstvan V: The Alpha Legion fought on the traitors' side at the Drop Site Massacre.
• Covert war: The Legion fought a secretive campaign, which included attacks on the Imperium's own preparations and plans.
• Eskrador: Guilliman is said to have killed Alpharius, but the truth is disputed.

Personality

Calculating, opaque and confident in hidden purposes.

They are calculating and secretive, always planning several steps ahead. Their love of misdirection makes them difficult to read, even for their own Legion. They believed that the ends justify the means, and their true goals remain hidden.

Weapons & Vehicles

Guardian SpearMelee Weapon

The iconic auramite halberd-and-bolter of the Adeptus Custodes and Deathwatch Watch Masters, marrying a crackling power spearhead with …

Power SwordMelee Weapon

A master-crafted blade sheathed in a crackling molecular disruption field that parts ceramite, bone and steel with effortless lethality…

Bolter & Bolt RifleRanged Weapon

The signature .75-calibre rocket-propelled mass-reactive firearm of the Adeptus Astartes, firing self-propelled explosive bolts that de…

Plasma Gun & Plasma IncineratorRanged Weapon

A volatile directed-energy rifle that hurls bolts of miniature sun-hot plasma capable of vaporising Terminator plate and tank armour—at…

Scout SquadElites · Unit

Neophyte Space Marines who are not yet fully implanted, fighting as infiltrators, snipers and raiders.

Explore all 48 entries in the Weapons & Vehicles armoury.

Connections

Characters (3)

• 
  The Emperor of Mankind creator · Imperium of Man

  The twin Primarch of the Alpha Legion; the details of their discovery are deliberately confused.

• 
  Roboute Guilliman enemy · Ultramarines

  Old lore said Guilliman killed Alpharius at Eskrador; later accounts complicate this.

• 
  Horus Lupercal ally · Black Legion

  The Alpha Legion sided with Horus, though their true motives remain debated.

Factions

• Alpha Legion primary faction

Some links are thematic parallels (marked "parallel") rather than recorded meetings. See the connections web.

Legacy

The Alpha Legion's legacy is a web of deception that no one fully understands. Its cells operate across the galaxy, sometimes appearing to aid the Imperium. Whether either twin survives, and whose side they truly serve, remain among the setting's most enduring open questions. The Alpha Legion's hydra-cell structure and its refusal to commit openly to any Chaos god keep its goals uncertain, much as the primarchs intended.

Appearances & sources

• The Horus Heresy novels Legion and The Serpent Beneath (Dan Abnett)
• Alpharius: Head of the Hydra (Rob Sanders)
• Codex: Chaos Space Marines (Alpha Legion background)