Heartstriker is the designation given by Jariah Syn to the Yuuzhan Vong amphistaff that he successfully domesticated on Wayland during 137 ABY.
The surface of the planet Wayland was largely covered in Yuuzhan Vong biotechnology in 137 ABY. The Yuuzhan Vong's attempts to restore the ecosystems of the devastated world eleven years earlier were undermined by agents working for the One Sith, which led to flora and fauna becoming infected with the Vongspawn virus and mutating into violent, hostile creatures. Among these creatures were amphistaffs—serpentine organisms frequently utilized as quarterstaffs by Yuuzhan Vong warriors—and in 137 ABY, one such creature encountered the Humans Jariah Syn and Fionah Ti within a damutek structure. As it prepared to strike, Syn began communicating with it in the Yuuzhan Vong language. Having learned the customs of the warrior caste from a Yuuzhan Vong warrior in his youth, he was able to pacify the amphistaff. Syn then named the creature "Heartstriker" and commanded it to obey him. Heartstriker immediately complied, coiling itself around its new master's waist.
Syn would later employ Heartstriker to eliminate Zenoc Quah. Following their departure from Wayland, Heartstriker remained affixed to Syn's arm. Syn subsequently brought it to Nal Hutta, where Cade Skywalker was in a meeting with Vedo Anjiliac Atirue and Queen Jool. It also accompanied him to Utapau, where it played a role in thwarting an assassination attempt targeting Galactic Alliance Remnant Admiral Gar Stazi.