The Star Wars Battlefront Sensor Droid card will deploy a probe droid that will maneuver around the map and scan the area for enemies to attack. Once the probe droid finds an enemy it will begin attacking them automatically, which makes it fun to deploy.
Also, the closer you are to an enemy probe droid the easier and quicker it is for it to lock onto you and begin to track your movements. So if you do happen to see one while you are playing Battlefront, stay as far away as possible to avoid becoming its next kill.
If you would like to discuss the Power Ups then visit our Battlefront Power Ups forum.