The Reaver Titan Praetorian
The Legio Astorum is a Loyalist Titan Legion of the Collegia Titanica, one of the military arms of the Adeptus Mechanicus. The Legio Astorum is an ancient and honoured Legion based upon the Forge World of Lucius, located in the Segmentum Obscurus. This Titan Legion is suspected to have been founded before the Age of the Imperium, during the Age of Strife.
The Warp Runners fought throughout the Great Crusade and still retain a number of Titans blessed by the Emperor of Mankind himself. Later, the Legion fought throughout the darkest days of the Horus Heresy, and participated in numerous engagements including the Battle of Tallarn. Legend has it that a battlegroup of Legio Astorum Titans was present at the defence of the Emperor's Palace during the Battle of Terra and ever since those dark days of the Great Betrayal, the Warp Runners have continued to faithfully serve the Emperor and His Imperium.
Reaver Battle Group - Vraks
During the infamous Siege of Vraks, the Legio Astorum Titan battlegroup provided the Imperial 88th Siege Army with its heaviest armour and firepower. Deploying 22 Titans of the Reaver and Warhound classes, the commitment of this battlegroup in support of the 12th Line Korps was the decisive factor in breaking through the inner defence lines during the Kagori offensive on Vraks Prime. The High Princeps Rand Drauca and his Warp Runners continued to support the campaign on Vraks on numerous occasions, and were heavily engaged again when the Red Scorpions Chapter captured the breach in the curtain wall, matching weapons and armour with the Traitor Titans of the Legio Vulcanum I. The exact number of enemy Titans was not identified, although post-battle reports claim that 14 enemy Warhound-class Titans and Reaver-class Titans were destroyed during the campaign. As such, the Legio Vulcanum paid a heavy price for its involvement, and the Legio Astorum can claim a famous victory over their ancient enemy.
When the Forces of Chaos assaulted the world of Cadia during the 13th Black Crusade in 999.M41, the Legio Astorum was one of the Loyalist Titan Legions of the Collegia Titanica to help in the defense of that beleaguered Imperial Fortress World. The Warp Runners fought in multiple campaigns during this Black Crusade, including the world of Amistel Majoris (located in the Agripinaa Sector was besieged by Plague Marines of the infamous Death Guard Traitor Legion. Despite the planet being reduced to a mass of putrefying corpses, the Imperial Guard's 83rd Regiment of the Drookian Fen Guard helped bolster Imperial forces with a masterful defensive strategy which kept the planet in Imperial hands until the arrival of additional Imperial forces in the form of the Howling Griffons Space Marine Chapter and the Titans of the Legio Astorum.
When the Skitarii forces of the Adeptus Mechanicus' Forge World of Demios Primary were scattered by the combined Chaotic forces of the Black Legion and the Extinction Angels, it was the Imperial defenders of the Legio Astorum and the Space Marines of the Black Templars Chapter which liberated the world's forges.