Ashrah was once a member of Quan Chi's Brotherhood of the Shadow, a group consisting of Netherrealm demons who worshipped the fallen Elder God Shinnok. One day, Ashrah refused to carry out one of Quan Chi's orders. In response, he sent her sister - a fellow member of the Brotherhood of the Shadow - to kill her. While escaping her would-be assassin in the Netherrealm, she found a holy sword known as the Kriss. As she learned how to wield the blade, slaying Netherrealm demons with it, Ashrah began to recognize that with each one she killed, the sword progressively cleansed her spirit of evil. She then resolved to liberate herself from her inherent malevolent nature by using the Kriss to eliminate the evil within her. Each demon that she slays brings her closer to her goal of purification, and consequentially, her eventual expulsion from the Netherealm, as that dimension cannot sustain anyone with a soul containing such purity. What she didn't know, however, was that her Kriss blade was actually the "Datusha", a mystical vampire-slaying weapon that corrupts its wielder with the false belief that they are using it for a greater purpose in order to continue it's genocide against the vampires and other demons.
At some point in the past, Ashrah allied herself with Shujinko and taught him demon slaying techniques. Also at another time, she came into conflict with Ermac. Mistakenly believing him to be a demon, she attempted to kill him however she was defeated. During the events of Deception, she searched for Noob Saibot, whom she considers to be a powerful demon, in order to slay him as doing so would enable her to complete her ascension.
Ashrah's bio in Mortal Kombat: Armageddon explains that, after slaying a multitude of demons in the Netherealm, she transcended that plane of hell and emerged in an unfamiliar realm, surrounded by celestial beings of light. The celestial beings made her into their chosen warrior - the wielder of the Kriss who could purify the world, and would ascend into becoming "an angel of light", once she used the weapon to "consume the darkness". After submitting to their will, Ashrah was transported to Vaeternus to start slaying the vampire race, whom she saw as vile beings for their feeding on the blood of the living and spreading their corruption throughout the realms. Ashrah began her quest, slaying numerous vampires. However, she soon was encountered by Nitara, who was warned of this threat to her realm by the elders of Vaeternus. Ashrah was defeated by Nitara, who then managed to escape to Edenia, and Ashrah followed her to gain the power of Blaze in order to destroy Nitara and gain ascension.
In Ashrah's Armageddon ending, the power of Blaze purified her completely; she was transformed into a being of divine light. Her radiance soothed even the darkest of souls. With new purpose, she traversed the realms in search of evil, pacifying the wicked. Her mission came full circle when at last she purified the sorcerer who would have her slain: Quan Chi.