The Master Control is a special feature of the Omnitrix that Ben Tennyson unlocks in order to be an alien for as an unlimited amount of time and becoming any one of his Omnitrix aliens with his thoughts. And able to use all of the Omnitrix features. The future episode, "Ben 10,000" , Ben unlocked the Master Control's code utilizing nanotech, as revealed during the Ben 10 Week. And in Ben 10 alien force Season two episode "war of the worlds", Azmuth unlocks the master control to defeat the high breed invasion. In alien force season three episode 1&2 "vengeance of vilgax" Ben and Kevin try to unlock the master control again to defeat vilgax. but while trying to "hack" the omnitrix they damage it resulting in four of the Omnitrix aliens escaping and fusing Kevin with different elements.