The Decepticons discovered a huge deposit of korlonium crystals and, instead of simply mining the energy contained in them, hatched an overly complicated plan involving a fake clone of Optimus Prime in order to lure the Autobots into it. Once the false Prime had infiltrated the Autobot ranks, Megatron was able to use energy amplifiers to cause an apparent increase in energy from the korlonium, luring the Autobots to the location.