On Cozan, Ridates squad came up against a Daemon, who haunted them and directed its soldiers against them. Ridates squad was caught in a deadly crossfire with Chaos forces in a gully, and the entire squad went down in less than six minutes. Khiron only survived (with his cheek and nasal bones broken) due to chance, when a stray shot brought down the gully wall and buried him in rubble. As Khiron lay buried, the Daemon - believing he was dead - passed right by him, leaving Khiron with knowledge of its unforgettable smell. When Khiron emerged from the rubble, all he could do was dig the progenoid glands out of his Marines' body. Thebes squad later overran the daemon's minions, but it fled and hid in the wounded Brother Krates. Blinded by the daemon's glamour, Thebes squad brought Krates back to the Chapter House on Karybdis. But Khiron recognised the daemon, and immediately took a gun to Krates, killing him. Thinking Khiron has lost his mind to Chaos, his fellow Marines jailed him in the Tholos beneath the Chapter House. Khiron then realised that he had in fact not killed the daemon, since he had used a gun instead of fire, and that it has moved onto another host. But no one would listen to him.
When Damocles Squad returned to Karybdis, Sergeant Priad requested Khiron as a replacement Apothecary for his squad's own deceased Memnes, and was denied. He then went to visit Khiron in the Tholos to investigate the stories of his madness. Khiron warned Priad of the daemon, and informed him that he has asked for Oethanar in two sunsets. Priad later sensed the smell of the daemon in Captain Skander of Phocis Squad during a combat drill and attacked him, eventually killing both him and the daemon with a flamer. Priad then embarked with Damocles Squad to the Primarch's Causeway on Ithaka to rescue Khiron from the Oethanar. They managed to reach Khiron before the Wyrms could devour him, and later instated him as their squad's Apothecary.