For years he waited. For years he planned. For years he sat in the shadows of the arena in Kaon watching as Transformers fought and died. As the taste for destruction grew within those who fought, he sowed seeds of his own rise to power, and the subjugation of Cybertron. Those who proved themselves worthy through a talent for viciousness or simple, raw power, he recruited. No more would they call themselves Transformers. Now they are Decepticons.
When the time came, his Decepticons rose up all over the planet. In that first lightning strike, thousands ceased functioning. So far, all of his planning has gone perfectly. Before his assaults, the Autobots are helpless, capable of fighting only long enough to barely manage a retreat to the next fallback position. All the while, his plan progresses. The Autobots will be destroyed utterly, Megatron thinks, the universe subjugated beneath my immortal heel, and the history of my conquest read by the flickering flames of a thousand burning civilizations.