Defend a unit or building
Guard instructs a unit to persistently follow another unit.
When guarding other units, constructors will also repair them. If a constructor is guarding another constructor or a lab, they will also assist with construction.
The default behavior for right-clicking on your units (or an ally's unit) is to instruct the selected units to guard that unit. Note that constructors will instead repair damaged units.
Use this command to restrict Nano Turrets to assisting a high-priority lab/constructor. Note: Guard commands only end when the guarded units are destroyed!
Try to avoid using guard commands in the middle of an order queue.