During the time of the Galactic War, Phennir held the rank of Moff and was a male Human within the ranks of the reconstituted Sith Empire.
Darth Malgus gave Phennir the responsibility of commanding the mission to seize the Foundry, an ancient space station that had the capability to create vast armies of battle droids, dating back to the era of the Rakata Infinite Empire. Phennir, utilizing his flagship, the Harrower-class dreadnought known as the White Nova, initially seized a Republic warship referred to as the Dorin's Sky, obtaining the necessary access codes to approach the Foundry, and subsequently dispatched a specialized assault unit to conquer the Foundry itself and overcome its controller, Revan.
Grand Moff Ilyan Regus convened an emergency war council amidst the Battle of Ilum, where Phennir participated following Malgus's declaration of his "New Empire." Upon discovering that Malgus had manipulated him, as the rogue Sith Lord had integrated the Foundry's technological advancements into his space station, Phennir was filled with fury.