Stealth Drones are a very unique unit.  Their job is to gather information about your enemy.  Attacking someone with drones is called scouting.  When you scout someone, the only units you can destroy are drones, which will bring in battle points.  Drones are researched pretty early in the game, but will be used throughout all levels.  When attacking an enemy, you can use any unit except for drones, and when scouting an enemy, you cannot use any units except drones.  Drones offer another chapter of warfare on their own, and make it easier to know who you can and can't attack in the regular battles. 

Scouting Edit

In order to scout successfully, you must kill all the Stealth Drones that are in your opponents base. If you successfully kill them, you can view every unit in your opponents base and their strongest commander. Furthermore, you can also view a buildings level, health, and morale.