Before she took the Oath of Repentia, however, Osyth was a Sister Superior charged with defending Daronch's outer shrineholds, when the Ork Warboss Grashbakh invaded the world. The Orks' sheer numbers, though, led them to overwhelm the Sisters under Osyth's command and they died while she survived. The Xenos also desecrated the shrines and destroyed relics and thousands of years of history. This led Osyth to become a Sister Repentia, and claim the name Penance, as she was no longer worthy of caring her original name. Osyth was among the Sisters that survived the loss of the Order's fortress when it was captured by Grashbakh, but the later arrival of the Black Templars' Edioch Crusade, however, gave the world's population a chance at survival. The Templars, led by Marshal, Adelbert, and the surviving Sisters of the Valorous Heart, led by Canoness Aurea, were then able to fight their way to the fortress, which the Warboss now ruled from.
As they advanced into the fortress, though, the Orks deployed an explosive attack on Osyth's position, which caused the ground to collapse. While she emerged unscathed, Osyth found herself alone within the tunnels, that lay beneath the battlefield and led into the fortress itself. She soon, however, found the Crusade's Emperor's Champion Cenric, who had also survived the ground's collapse. Together they fought their way to Warboss Grashbakh's sanctum within the fortress, which luckily for them was undefended, as the battle still raged on. While he was outnumbered, Grashbakh still proved to be more than a match for the two of them, until Osyth rushed at the Warboss with a Krak Grenade. Though, the Warboss was able to grab hold of the Sister Repentia, Osyth sacrificed herself by activating the grenade. With that act she gained the redemption she had sought and earned back her name, as the resulting explosion killed her and heavily wounded Grashbakh. This allowed Cenric to kill the Warboss and Grashbakh's horde within the fortress was destroyed by the Crusade and Osyth's Sisters.