Terror Drone Surprise is a Soviet Top Secret Protocol. This protocol allows Soviet commanders to place Terror Drones in their vehicles which are released when the vehicles are destroyed. In the game, whenever a vehicle is destroyed, there is a 75% chance that a Terror Drone will spawn in the wreckage of the vehicle. This upgrade is especially dangerous toward Tanya (though in newer patches, Tanya can destroy Terror Drones) and melee units such as the Steel Ronin and Grinder. This upgrade is also needed to unlock the Toxic Corrosion and Orbital Drop/Dump/Downpour Support Powers in skirmish mode and in the Commander's Challenge in Uprising.