Perimeter Scanning Drones are spherical mechanical drones that either stay still, or track the player. The explode dangerously when shot or when near the player. The player should always try to keep their distance from active PerScan drones and destroy them from a safe distance.
PerScan drones have some unique features. It is the only enemy that shows any sort of damage, as shots that do not destroy it will leave dents and marks on it. It is the only actor that can harm another actor and possibly kill them, with the explosion. If this happens, Blake receives credit for the kill.