Koronis was promoted to executor and assigned to lead an expeditionary fleet from the carrier Qel'Ha. He was tasked with recovering xel'naga artifacts and apprehending Dark Templar. Koronis did not regard the Dark Templar as a threat but was willing to carry out those orders under the supervision of Amdor, his Judicator advisor. Many decades of searching failed to turn up either objectives and Koronis was still deployed with the fleet when Aiur was devastated by the zerg, only to be saved by Tassadar. Unlike Amdor, who saw the former executor as a heretic, Koronis regarded Tassadar as a hero.
The fleet prepared to return home after decades of fruitless searching until they detected signal from the newly uncovered xel'naga artifact on the terran world of Bhekar Ro. Koronis recognized some of parts of the signal as forming an "urgent" message and, with Amdor's approval, ordered the fleet to the planet. When the scouting observer was destroyed by a missile turret, Koronis at first counseled caution but was convinced by Amdor it was unnecessary: the terran colony was small, primitive, and posed no threat.
Despite his unease the executor led the ground forces to the surface and secured the artifact. After he landed on the ground the protoss encountered the zerg Kukulkan Brood in orbit and realized the zerg had arrived first. Koronis directed the defense of the artifact against the zerg and, later, the Terran Dominion's Alpha Squadron. The latter suffered heavy casualties as a result. During the battle, Koronis used the khaydarin crystals surrounding the temple to manifest a powerful psionic storm, but was left exhausted by the effort.
When the Dark Templar Xerana arrived Koronis was willing to hear her warning that the temple was dangerous. However Judicator Amdor quickly seized control of the situation and ordered that outcast be arrested. After Xerana's escape the executor declined to accompany the Judicator into the artifact, citing his responsibility to remain outside and direct the battle. Koronis survived the terran nuclear strike thanks to the artifact's energy absorbing properties but was himself absorbed, along with the rest of the protoss and zerg by the energy creature that was birthed shorty thereafter.