The following section contains information from StarCraft: Retribution.
Cerebrate of the Sennith Brood
Zargil told his charge, a young cerebrate, about the importance of the Argus Stone. Knowing Terran Dominion scientist Jenson Archimedes possessed the Stone, he ordered the new cerebrate to use the Zerg Crusaders to destroy Archimedes' battlecruiser escort.
Archimedes roamed among multiple terran bases in the area. Zargil ordered the new cerebrate to infest a science facility so Zargil could extract information from the people within, helping him find Archimedes.
Zargil was distracted by the course of the war; a hive cluster had fallen under attack. However, the terran and protoss forces fought with each other, giving the zerg the advantage. The new cerebrate was ordered to reclaim the hive, then fight the enemies.
Zargil was able to continue the quest to capture the Stone. He discovered a terran military base/scientific installation, and ordered the new cerebrate to capture a command center. From them, he intended to extract information on the Stone's precise location.
Another Brood attempted to recover the Stone from a scientific installation, but failed. The new Cerebrate was ordered to make its own attempt, with assistance from infested terrans who had knowledge of the facility, such as passwords. Within the installation, the Zerg Crusaders were to rescue Thakras, a powerful defiler, and use its Plague ability to defeat the installation's ghost defenders. The Stone was acquired for the zerg.
Zargil gave advice in defending the Stone as the zerg forces retreated to Char. Once there, they fought a major battle against the terrans and the protoss. Victorious, the zerg used the Stone to fashion the "supreme being".