Sehtra was a female Human Sith Lord of the Sith Empire during the Cold War and Galactic War. A talented sorceress, Sehtra's body began decaying rapidly by the time she became a Sith Lord and, fearful of death, began looking into methods of extending her life. She stumbled across old stories concerning Sith who had supposedly moved their spirits into the bodies of others and developed her own variation of the ability, using it to claim the body of Tallie Odé.
Unfortunately, Sehtra's technique was imperfect and exacerbated the issue of dark side degradation, causing Sehtra's new body to begin decaying rapidly and prompting her to target her apprentice as her new host. Initially she tried to convince her strongest student, Galen Andriche, to surrender his body willingly through lies and flattery, but Galen fled with his partner and attempted to reach Republic space to escape his master. En route, he was intercepted by agents of Lord Benjamin Lambert and persuaded to help ensnare Lord Sehtra, using himself as bait, ultimately allowing Lambert and his allies to find Sehtra on Yavin IV, where she had – through Lambert's own master, Darth Knossai – allied with the Order of Revan.
Joined by Jedi Shadow Avexiss Odé, his apprentice Damascus and his wife Lexine, Lord Lambert was able to thwart Knossai's attempts to rally Massassi reinforcements to Revan's cause and finally corner Sehtra in a confrontation she could neither win nor escape from. Desperate, she used the last of her immense power to move herself through space, retreating to the Dark Temple on Dromund Kaas and bringing herself to her stolen body's limits. While attempting to recover in the Dark Temple, the body-shifting Sith Lord was tracked down and confronted by both Lambert and Odé, with the former allowing the latter to confront her alone, to avenge her sister Tallie.
Barely able to move, Sehtra made a desperate attempt to transfer her essence into Odé's body; unbeknownst to Sehtra, however, was that Avexiss had faced a similar mental invasion several years earlier, one that had been partially successful, and alongside her own not-insubstantial mental resistance a parasitic dark side entity was entangled within her own essence. Facing overwhelming resistance, Sehtra's last moments of awareness were spent in spiritual agony, as the entity that had anchored itself to Odé not only helped her shrug of the Sith Lord's intrusion, but also shattered Sehtra's consciousness and consumed her essence. Although Sehtra's quest for immortality had ended in failure, she had been rendered nonexistent, and thus she had avoided ending up in Chaos, as she had feared for so long.