Board Thread:Questions and Answers/@comment-74.101.78.45-20131123190454/@comment-9028463-20131213021730

74.101.78.45 wrote: The ability of the sub is to instant kill anything but if theres a zomg behind a zomg, the front one spawns 4 bfbs and the back one doesn't die. Why is this happening ;-; if you read the description of the upgrade, a devastating missile strike on the largest bloon on screen, destroys up to a Z.O.M.G bloon in one go, "or many lesser bloons"

it probably depends on not only the strength of the bloon but the number of bloons. (which also explains the "splash damage" dealt.)