In 137 ABY, the surface of the planet Wayland was covered with Yuuzhan Vong biotechnology. Efforts by the Yuuzhan Vong to restore the devastated world's ecosystems eleven years prior had been sabotaged by agents of the One Sith, and as a result, flora and fauna infected with the Vongspawn virus mutated into violent and hostile creatures. Included in their number were amphistaffs—serpentine beings often employed by Yuuzhan Vong warriors as quarterstaffs—and in 137 ABY, one such creature discovered the Humans Jariah Syn and Fionah Ti inside of a damutek structure. As it reared to attack them, Syn began to speak to it in the Yuuzhan Vong. He had been taught the ways of the warrior caste by a Yuuzhan Vong warrior in his youth and was accordingly able to calm the amphistaff down. Syn named the creature "Heartstriker" and implored it to submit to his will. Heartstriker immediately acquiesced and coiled around its new master's waist.
Syn would later use Heartstriker to kill Zenoc Quah. After leaving Wayland, Heartstriker remained attached to Syn's arm. He would bring it to Nal Hutta, where Cade Skywalker was meeting with Vedo Anjiliac Atirue and Queen Jool. It would accompany him to Utapau as well, where it was used to foil an assassination attempt on Galactic Alliance Remnant Admiral Gar Stazi.
- Legacy 44: Monster, Part 2 (First appearance)
- Legacy 46: Monster, Part 4
- Star Wars: Legacy: Extremes
- Legacy—War 3