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 these Titan Legions turned traitor during the Horus Heresy, even before the Horus 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 in and of itself. The Forges of Stygies VIII are known to be the homes of some of the best munitions artisans in the Imperium, they produce the best gun barrels, recoil dampeners, and finest quality propellent chemicals and is second only to Mars itself in these fields, and it is one of only three known Forge Worlds capable of producing Vanquisher Cannons on a large scale. Although after the Forge World of Tigrus was overrun in M35 by the Ork Warlord Arrgard the Defiler and the Forge World of Gryphonne IV was consumed by Hive Fleet Leviathan, the production of Vanquisher Cannons has fallen mostly to Stygies VIII. The Forges of Stygies VIII are also known for producing the most common pattern of Imperial Guard Manticores.
During the Horus Heresy Stygies VIII almost fell to traitor forces under the command of Warmaster Horus, yet was saved by the intervention of Eldar forces, afterwards the planet became home to a secret sect 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 in three separate sources as being located in three different Segmentums, in Imperial Armour Volume One it is given as being in the Ultima Segmentum, in White Dwarf 260 (UK) it is listed as being in the Segmentum Obscurus, and most recently in the Horus Heresy - Book One: Betrayal it is shown on a map as being located in the Segmentum Pacificus. As the Horus Heresy - Book One: Betrayal is the latest of the three sources to be released the Forge World will be listed as being 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