Burrow
Source: Hatchery
Minerals: 100
Vespene Gas: 100
Research Time: 80
This ability is available to several Zerg grounds units including the Drone. A burrowed unit will dig itself into the ground rendering it invisible and cannot be attacked unless a nearby detector unit can spot its location. The burrowed unit cannot attack any units, but it can see a very small distance. This ability is great for hiding your injured units to allow them to recover health or for spying at certain locations, such as expansion points or outside enemy bases to track enemy movement.