Vorx is a Chaos Lord and a Siegemaster of the Death Guard Traitor Legion as well as the commander of the powerful warband of Death Guard Heretic Astartes known as the Lords of Silence. Vorx played a major role in the conquest of the Imperial world of Sabatine, the former Chapter planet of the White Consuls Space Marine Chapter, transforming it into a Daemon World dedicated to the Plague God Nurgle.
Vorx was among the first Aspirants taken from Barbarus to join the Death Guard Legion after the Primarch Mortarion was rediscovered by the Emperor and given command of the XIV Legion. Vorx took part in many of the battles of the Great Crusade and eventually rose to become a Death Guard fleet commander, known as a "Siegemaster" within the Legion.
When the Horus Heresy began, Vorx willingly joined his Primarch in turning upon the Imperium, for his loyalty was to Mortarion, not to a distant ruler on Terra. After the Warmaster Horus' forces were defeated in the Battle of Terra, Vorx fled with the other Traitors into the Eye of Terror in order to escape the Imperium's wrath during the Great Scouring. It was within the that Warp rift, at some unknown date, that he founded the Lords of Silence, which later become one of the Death Guard's most powerful warbands.
During the 13th Black Crusade, after the Fortress World of Cadia fell to the assault of Abaddon the Despoiler, Vorx and the Lords of Silence were among the Death Guard forces deployed alongside other servants of the Ruinous Powers to assault the Forge World of Agripinaa under the command of the World Eaters Chaos Lord Kossolax the Foresworn. The Astra Militarum troops of the Cadian Diaspora -- those who had survived the fall of that world or been elsewhere at the time of its destruction -- proved decisive in the world's defence, and the forces of Chaos once again were repulsed from Agripinaa.
After the opening of the Great Rift in ca. 999.M41 in the wake of the 13th Black Crusade, Vorx and the Lords of Silence allied with the Weeping Veil warband of the Word Bearers and attacked Sabatine -- the homeworld of the White Consuls Space Marine Chapter. Vorx and the Lords of Silence managed to not only defeat the White Consuls, but Vorx personally killed their Chapter Master Cymar Xydias before driving what remained of the Chapter off-world.
Next, the Lords of Silence, at Vorx's direction, were able to disupt the Weeping Veil's attempt to claim the remainder of the world's population as sacrifices to bring three daemonic legions led by Greater Daemons to the world by transforming them all into Plague Zombies and Poxwalkers before the sacrifice could be undertaken. The Word Bearers departed the now-useless world, leaving the Lords of Misery to transform it into a Daemon World dedicated to the pursuit of all-new diseases and pathogens.
In a short time, Sabatine had essentially become a veritable copy of Mortarion's own Plague Planet in the Eye of Terror. But Vorx remained uncertain about what should be his next course of action -- to remain on Sabatine and oversee its continued metamorphosis into another extension of the Plaguelord's realm in realspace -- or join with his Primarch in the great assault upon the Realm of Ultramar that became known as the Plague Wars.
- The Lords of Silence (Novel) by Chris Wraight, Chs. 3, 15, 19, 21, 22
- Warhammer 40,000: Rulebook (8th Edition), pg. 50