Forge Worlds are the worlds of the Adeptus Mechanicus – worlds totally devoted to industry and to the Cult Mechanicus’s own occult worship.
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A forge world is directly controlled by the Adeptus Mechanicus. All are completely dedicated to the manufacture of the various machines of the Imperium, the pursuit and preservation of humanity’s ancient scientific knowledge and the worship of the Machine God. Ancient pacts between the Adeptus Mechanicus and other worlds and institutions of the Imperium oblige the various Forge Worlds to supply other worlds and the various military arms of the Imperium, such as the Imperial Guard. Based on most forge worlds are the Titan Legions; these are supported by legions of Skitarii, the Mechanicus’s cybernetically-enhanced soldiers, who also serve as the forge worlds’ military forces. Equipment produced by forge worlds are constructed according to the individual forge world’s own design-standards or “patterns”.
Agripinaa is a Forge World located close to the Eye of Terror and is the principle supplier of arms to the entire Cadian Gate region. Agripinaa exists upon the threshold of the Eye of Terror. Were it not for the defences of the Cadian System it would have fallen long ago. The planets technological bounty has led many Warpsmiths of Chaos to raid the planet, including several full-scale invasions. This has left its surface with a battered and scarred appearance. In exchange for protection, Agripinaa provides the Cadian System with most of its armaments as well as supplementing them with Skitarii forces. Agripinaa does not sit solely on the defensive however. They have a history of dispatching war fleets into the Eye of Terror to crush Forge Worlds of the Dark Mechanicus. One notable campaign was against the Dark Forge of Temporia.
Due to its proximity to the Cadian Gate, Agripinaa suffered greatly during Abaddon the Despoiler’s 13th Black Crusade. The planet was invaded by an enormous World Eaters army under Kossolax the Foresworn, who sacrificed millions of its citizens over forty hours to summon a horde of Khornate Daemons, including a Bloodthirster. Eventually however, thanks to four companies of the Blood Angels, the World Eaters and their Daemonic allies were defeated and pushed off the devastated world. Following the destruction of Cadia in the Thirteenth Black Crusade, Chaos forces launched another assault on Agripinaa. Daemon Engines led by many Warpsmiths invaded the Forge World. The Cadian Diaspora proved decisive in the worlds defense. Agripinaa is known to produce its own patterns of autogun and is known that Leman Russ Eradicators built on Agripinaa are particularly prized for the accuracy and reliability of their Nova Cannons.
Graia is an Imperial Forge World and home to the Legio Astraman. Though the Adeptus Mechanicus does not make it widely known, the principle Forge networks of Graia known as the Graian Crown is capable of independent flight. Giant fusion engines allow it to escape its host planet’s gravity and move to the nearest Mandeville Point, where it can then travel through the Warp. The last time Graia attempted this, it was assaulted by an invasion fleet of Necron aircraft that soared up from the Laochan Gate. Though Imperial records currently claim that Graia’s priesthood have returned to circumnavigate their original home world, at least one recent Rogue Trader report lists the planet’s orbit as strangely empty. Graia is known to have its own patterns of Hellhound and Rapier Laser Destroyer.
It also produced an experimental version of Space Marine Grenade launcher known as Vengeance launcher and created its own Manticore pattern. Note, that while the missiles on Graia pattern Manticore are the most noticeable difference from more common Stygies VIII pattern, these are incendiary missiles and are not related to Graia pattern, which differs from Stygies VIII version by tower details.