In 2372, Regent Worf placed his younger brother Kurn in command of the Ya'Vang after he learned that the House of K'Tal had betrayed the Alliance. Kurn had been hoping that he would be given command of the Regent-class IKS Gorkon. However, that assignment went to Klag, who played a key in role in revealing the existence of the betrayal. (KE - Mirror Universe short story: "Family Matters")
In 2375, while still under Kurn's command, the Ya'Vang served as the former Intendant Kira Nerys's flagship while she was hunting down the hidden Terran Rebellion shipyard which was located in the Badlands. She came out of warp and managed to destroy the shipyards, all eleven Defiant-class warships under construction there, and a lot of the rebel leadership. At that point, the Ya'Vang then disabled Capital Gain and captured rebel leaders Generals Julian Bashir and Zek.