Following the ascension of Varis zos Galvus to the throne of Garlean Emperor, he and his favored Legatus learned about Archbishop Thordan VII's plans to reach the forbidden land of Azys Lla. Bringing the newly constructed super-dreadnaught, Gration, the VIth Legion established an outpost on a cluster of floating islands in the Sea of Clouds, and soon learned of the Vanu Vanu's primal Bismarck.
Attempting to track the Archbishop when he and his Heavens' Ward set off to find the key to Azys Lla, several legionaries harassed the peaceful Ok'Zundu tribe of Vanu until they were driven off by the Warrior of Light and Alphinaud Leveilleur. While the Warrior of Light battled the primal Bismarck, Regula and his legion occupied Ok'Zundu, not bothering to distinguish them from the Vundu tribe that actually summoned the Lord of the Mists. Upon returning to the village, Alphinaud and the Warrior of Light came face-to-face with Regula van Hydrus and Varis zos Galvus themselves. The occupation of Ok'Zundu was lifted thanks to the Temple Knight Lucia goe Junius (a Garlean spy that defected to the Holy See), who attacked with her magitek reaper, forcing the Legatus and Emperor to withdraw.
Unfortunately for both parties, the Archbishop had seized the key to Azys Lla from the Warrior of Light thanks to the aid of the Ascians, and opened the way to the lost continent. Any attempts of pursuit by the Warrior of Light or the Garleans was stopped short by a massive force-field around the Allagan super-structure.
Only by building an experimental aetheric ram could Cid Garlond pierce the field surrounding Azys Lla. The Gration closed in on the Enterprise Excelsior attempting to shoot it down but their efforts were thwarted by the unexpected arrival of Hraesvelgr and Ysayle, the latter transforming into Shiva one last time to engage the Gration. Though the super-dreadnaught destroyed the primal and killed Ysayle, her sacrifice froze the Gration's engines in aetheric ice, forcing it to make an emergency landing and allowing the Warrior of Light to land on the continent.
The Gration moored at the Gamma Quadrant, where the VIth Legion set up a base camp called Castrum Solus. As the Warrior of Light and the Scions of the Seventh Dawn made their way through Azys Lla, they clashed with Regula van Hydrus and his legion. Y'shtola, Alphinaud, and Estinien Wyrmblood held off the Garleans while the Warrior of Light went on ahead, encountering Regula van Hydrus within the Aetherochemical Research Facility seeking to learn how the Allagans sealed primals. The Legatus was forced to retreat after a tense fight, leaving the Warrior of Light to handle the Archbishop and his Ascian allies alone.
Following the Warrior of Light's triumph over the Archbishop and the Ascians, the VIth Legion works on pilfering Azys Lla for the secrets on binding primals. Regula encounters the Scions once more, who work on keeping the Warring Triad contained. Despite clashing numerous times, Regula comes to understand that the Allagans technology at Azys Lla may not be the solution to primals he hoped it would be, and realizing the threat of the Triad, he proposes an alliance with the Scions to combat the last of the Triad, Zurvan. During the clash with the godly primal, Regula is killed but his sacrifice gives the Scions and the Warrior of Light the chance the need to subdue Zurvan.With their Legatus dead, the Scions allow the VIth Legion to transport Regula's body back to Garlemald for burial, having come to respect the Legatus and acknowledge his bravery.