Twohy took part in the unit's ill-fated mission to Vygoire, assigned to investigate a Dominion lab complex that had stopped responding to hails. Terrestrial and orbital observation showed that while the complex had suffered damage, it appeared to be from natural causes, such as a landslide. As per urban-recon protocols, the facility was investigated, the unit discovering human remains, but no living scientists.
The marines headed into the jungle. Sergeant Norwood Doakes assigned Chen to investigate a clearing that had a lot of bent and scarred trees. After returning to the group, he reported that there were large quadrupedal tracks through the clearing. As if on cue, a roar sounded through the area. It was at this point that Twohy started freaking out, screaming about coordinates, gods, and a "Great One." He ran into the jungle, and an ultralisk came charging back in his place, which proceeded to engage the platoon.
During the fighting, Twohy became pinned underneath a tree. As the ultralisk retreated from the platoon, it crushed him under its feet.