The biggest Avengers saga in Marvel history! Jason Aaron assembles the mightiest heroes of Earth, the Multiverse and 1,000,000 BC in the capstone to his incredible era of Avengers! From throughout time and across realities, they will unite on a day like no other, to face a battle beyond all imaging. A war that will take us from the prehistoric beginnings of a planet under assault by the greatest villains who've ever lived to the Watchtower that stands at the dark heart of the all and the always, where an army of unprecedented evil now rises - including Doom Supreme, his Multiversal Masters of Evil and a nigh-infinite army of Mephistos! But who is Avenger Prime?!