Ihsta is a temple high priestess to Moloc. Thirty years ago, Moloc declared that all female children of jaffa were to be sacrificed in the ceremony of fire. Ishta could not abide this, and used her position to save those children she could. As a high priestess, part of her duties was keeping birth-records and preside over the ceremony of fire, which gave her opportunities to spirit away the daughters, rather than let them burn. She and her seconds, Neath and Mala were allowed to travel via stargate, giving them opportunity to get their rescuees off world. As all but a few of Moloc's jaffa were steadfastly loyal, she had to be careful to keep her actions secret even from the parents. Soon, Ishta's small group became a major rebel movement with its own planet as base of operation. This movement became the Hak'tyl, all female. As the daughters came of age, symbiotes needed to be procured for them, so the Hak'tyl raided Moloc's jaffa, taking their essential symbiotes from them so that the girls might live instead of these men. However, the movement was growing too fast. The Hak'tyl needed allies for supplies and weapons. They turned to the Tau'ri and contacted SG-1. SG-1 offered an alternative to raiding for symbiotes, as they had the drug 'tretonin' as an alternative. Ishta offered to be the first Hak'tyl to test tretonin, but Mala insisted on taking her place, believing that Ishta was too valuable to risk. Ishta sent a total of four of her warriors to the SGC to test the drug. Meanwhile, Neath objected to the tretonin experiment and challenged Ishta to "Jome Seku". Ishta defeated Neath, but spared her. When Mala died in the experiment (the only one of the four to do so), Ishta chose initially to reject the tretonin. However, when a symbiote raid turned up one fallen jaffa who was of the rebels, she changed her mind. Ishta and the rest of the Hak'tyl turned to tretonin instead of symbiotes for their immune system.
Anxious to end Moloc's horrid practice of the ceremony of fire, Ishta and the Hak'tyl constantly pressed the other jaffa rebel groups to bring about Moloc's fall as soon as possible. She was opposed by Teal'c, who felt that the rebels should strike when they were ready to take on all of the goa'uld. Otherwise, another goa'uld would step in to take Moloc's place. She met with a council of rebel jaffa from Moloc's service to arrange this, but the council was ambushed. Only Ishta, Teal'c, and Aaron escaped with their lives. In order to rescue them, the SGC used missiles to assault Moloc and his forces, and Moloc was killed. As Teal'c predicted, another goa'uld stepped in to take his place.
Ishta raised one of the girls she rescued, Ka'ryn, as a daughter. Ishta was quite proud when Kar'yn married Rya'c, the son of Teal'c.