The Autobots and Decepticons' uneasy peace is threatened by the flames of war! Starscream, ruler of Cybertron, makes contact with Windblade's homeworld-and the only defense against a new Cybertronian Empire is the Combiners-multiple Cybertronians joining together into huge, dangerous forms!

Once he ruled CYBERTRON with a brutal (and literal) iron fist... left for dead four million years ago, SENTINEL PRIME is back. But in a world where STARSCREAM rules CYBERTRON, OPTIMUS PRIME has invaded Earth, and MEGATRON is an AUTOBOT-SENTINEL doesn't like what he sees!