Stygies VIII is an Imperial Forge World of the Adeptus Mechanicus that is located on the seventh and largest moon orbiting a massive gas giant on the outer fringes of the Vulcanis System in the Segmentum Pacificus of the Milky Way Galaxy. The planet is currently home to the Legio Honorum, a Loyalist Titan Legion also known as the "Deathbolts." The moon was previously home to both the Legio Vulcanum I and Legio Vulcanum II, but both of those Titan Legions turned Traitor during the Horus Heresy and Stygies VIII needed new Titan protectors. Even before the Heresy it was very rare for a Forge World to be home to more than one Titan Legion.
Stygies VIII is a large Forge World that produces everything from Imperial Guard infantry weapons and battle tanks to the mighty Battle Titans of the Collegia Titanica. It is known that Stygies VIII is a Production Grade II-Extremis Forge World with a Tithe Grade of Aptus Non, meaning it pays no tithe to the Administratum, as its industrial output is considered of potent strategic value for the Imperium of Man in and of itself. The forge-cities of Stygies VIII are known to be the homes of some of the best munitions artisans in the Imperium and they produce gun barrels, recoil dampeners, and propellent chemicals second only to Mars itself in quality. Stygies VIII was once one of only three known Forge Worlds capable of producing Vanquisher Cannons on a large scale. After the Forge World of Tigrus was overrun in the 35th Millennium by the Ork Warlord Arrgard the Defiler and the Forge World of Gryphonne IV was consumed by Hive Fleet Leviathan, Stygies VIII became the sole known producer of Vanquisher Cannons. The forges of Stygies VIII are also known for producing the most common pattern of Manticores used by the Imperial Guard
During the Horus Heresy, Stygies VIII almost fell to Traitor forces under the command of the Warmaster Horus, yet was saved from this fate by the unexpected intervention of Eldar forces, who had their own sake in seeing that the Forces of Chaos did not gain access to such a strategic treasure which might turn the Heresy in Horus' favour. After the end of the Heresy, the planet became home to a secret sect of the Cult Mechanicus known as the Xenarites, who are dedicated to the study of alien technology, particularly that of the Eldar.
The location of Stygies VIII has been listed as being located in three different Segmentae according to different sources. In Imperial Armour Volume One its location is given as the Ultima Segmentum, in White Dwarf 260 (UK) it is listed as being in the Segmentum Obscurus, and most recently in Imperial Armour's Horus Heresy - Book One: Betrayal it is shown on a map as being located in the Segmentum Pacificus. As the latter source is the most current of the three sources to be released, Stygies VIII is listed above as officially located in the Segmentum Pacificus.
- Imperial Armour Volume One - Imperial Guard and Imperial Navy, pp. 8, 11, 31-46, 178
- Imperial Armour - The Horus Heresy - Book One: Betrayal, pg. 11
- White Dwarf 260 (UK), pg. 65