During their September 29 set at the Louder Than Life festival in Louisville, KY, Spiritbox were joined onstage by several special guests. Among them were Poppy, who performed “Soft Spine,” Jinjer’s Tatiana Shmayluk, who performed “Circle With Me,” and Architects’ Sam Carter, who performed “Yellowjacket.” You can check out some fan-filmed footage of all three…