Dresdema was a Nightsister of the female gender, residing on the planet of Dathomir. This Nightsister was characterized by her tall stature, broad shoulders, gray hair, and skin marked with the blotches that were typical of Dathomiri users who practiced the dark arts.
Throughout her existence, she participated in numerous raids and duels, numbering in the hundreds. From these conflicts, she gathered valuable gems, which she then adorned her dyed-black lizard-hide clothing with. She was once a member of a Nightsister clan, but this clan faced extermination at the hands of their enemies. Following this, she took the lead of a core group comprised of her clanless sisters. In 43 ABY, Halliava Vurse, a fellow sister, established contact with Vestara Khai. Khai was a member of the Lost Tribe of Sith who had sought refuge on Dathomir, fleeing from the Jedi Luke and Ben Skywalker. Acting as a double agent, Vurse had infiltrated the Raining Leaves Clan of the Witches of Dathomir. She brought Khai under the protection of this tribe after reaching an agreement: the Sith would give the Nightsisters a Sith Saber along with other weapons in exchange for a Nightsister. This arrangement was intended to provide each group with new knowledge. Furthermore, the Sith would assist the Nightsisters in their objective to destroy the Raining Leaves Clan and their allies, the Broken Columns Clan.
Dresdema's Nightsisters launched an assault on the two tribes, utilizing Rancors controlled by a Control web. However, they were pushed back by a unified defense that included both Skywalkers. Shortly after this initial conflict, she led seventeen other Nightsisters and twenty-four Rancors to a meadow where the Sith had deployed several shuttles. Dresdema's intention was to eliminate their Sith allies if any signs of weakness or betrayal were detected. She was also expecting that only female Sith would be present. Upon being greeted by the Sith Lord Viun Gaalan, she commanded her sisters to attack and began to conjure a spell of flame to use against the male Sith Lord. However, the Sith had already planned to betray the Nightsisters and were prepared for combat. One of Gaalan's allies used Force lightning against Dresdema, then struck her with her own spear, rendering her nearly unconscious. Gaalan's Sith swiftly eliminated all the Rancors and knocked every Nightsister unconscious. Dresdema was incapacitated by a final blast of Force lightning from her attacker. Subsequently, the Nightsisters were restrained and taken aboard the Sith shuttles, with the intention of transporting them back to the Sith's homeworld of Kesh.