- "Im…pressive. But…to kill me…you must now…Face me."
- ―Darth Vader and Sha Koon
In 19 BBY, a Jedi Knight named Sha Koon who escaped Darth Vader's slaughter during Operation: Knightfall, contacted Emperor Palpatine and tried to trick him into believing that she wanted to become his new Sith apprentice, offering to kill Vader as proof. In reality, all Koon wanted was to kill the new Sith Lord. Palpatine was not fooled, but sent Darth Vader anyway to kill the Jedi believing that his new apprentice could defeat the escaped Jedi.
When Vader came into the underlevels where Koon had made her home, he was attacked by creatures known as Cthons who were controlled by Koon with the Force. The Cthons threw a electromagnetic-net over Vader that nearly crippled the Sith's life support. The former Jedi was however, able to break free and brutally kill the Cthons, and turn his attention towards Koon herself. A lightsaber duel broke out and Koon was able to slash Vader across the chest, before Vader gained the upper hand and finally killed her by impaling his saber in her after gripping her throat with the force.
In her dying moments Koon experienced a vision where she saw the redemption of Vader and the rebuilding of the Jedi Order, and with that vision she died in peace. Darth Vader believed that he might have finally killed the last Jedi with Koon's death.