However, after he lost his foot in one of the Crusade's battles, Luka was given a bionic replacement and given a promotion to Major. His injury though took him away from the Crusade's frontlines and charged with training a group of the Whiteshields serving in Ryse's forces. While doing so, they were placed under General Travis's command in the Gort System, which was supposed to be securely in the Imperium's hands. This was proven false though, when the Anckorite Brotherhood Cult later instigated a rebellion on the Gort world of Besana. Luka and the Whiteshields found themselves among the Imperial forces sent to defeat the Brotherhood, but the Cult proved to be unstoppable. Soon Besana was nearly in the Brotherhood's hands and the Imperial forces had begun retreating to the world's only spaceport in order to escape the Cult. The Major refused to retreat and, due to Besana's deadly desert environment, the Whiteshields were the only force blocking the paved path the Brotherhood needed to reach the spaceport. Luka then ordered the Whiteshields to fortify a ridge and told them they are Cadians and Cadians do not retreat. Besides he explained, even if they retreated the Brotherhood would reach the spaceport and wipe them out, before the Whiteshields could evacuate.
When the Brotherhood later attacked, the Whiteshields' position on the ridge allowed them to push the Cult back several times. This led the Cult to try walking on the Besana's deserts to bypass the Whiteshields, but any Cult members that did so were swallowed whole by slipsand pools. With no other choice the Cult then massed its strength against the Whiteshields, but due to Luka's command they held out, until General Creed suddenly appeared. Creed and the Cadian 8th had been sent by Warmaster Ryse to defeat the Cult and he thanked his old comrade Luka, for ensuring he would be able to do so. Thankfully the General had devised a battle plan to win, but it required the Cadians held the ridge for a day. Though they took heavy losses, the Cadians succeeded in doing so and the next day, the Grand Cruiser Magister Thine fired upon the Cult's position below the ridge. This devastated the Brotherhood and it retreated - directly into the Imperial forces Creed had ordered transported behind the Cult. Now trapped between both sides, the Brotherhood was wiped out and Besana was saved. Afterwards, Luka's surviving Whiteshields were promoted to Guardsmen of the Cadian 8th and Luka was given new Whiteshields to train.