Usually controlling constructor drones, the Virai Tertiary instance is always ready to mount a fierce defence in case of a threat.
To manage the inherent weakness of the Virai drone categories, a number of secondary- and tertiary- instance architectors are required in each force to provide command and control as well as to provide auxiliary services such as field repairs.
Tertiary Instances are often accompanied by numerous constructor drones. Though often integrated with their manufacturing or heavy machinery, tertiary instances detach themselves when forced into combat and lead their swarm of constructors to the defence of the colony.
The Swarm!
Sam Phillips