G.I. Joe: A Real American Hero (Marvel) – Issue 3A

An inert and dismantled robot is brought into the Pit, where it’s being studied. In a rare moment when it’s alone, it locks down the Pit and assembles itself, programmed to fight its way to the surface and transmit a homing signal to bring Cobra down on the Joes. With most of the team trapped under lockdown, there is very little resistance ready to stop it.