Robotech # 6: Doomsday by Jack McKinney

A war without victors, that had brought two races to the brink of extinction. A war without spoils, save for the devastated Earth itself…

A new-age ark, the Super Dimensional Fortress had returned to its ravaged homeworld, and those who had lived through Armageddon began the painstaking process of reconstruction. But they had the Zentraedi to help them, former enemies who shared a common goal — survival!

But all was not well in this bravest of worlds….Unaccustomed to a life without warfare, many of the alien giants were reverting to their old ways. Now one had appeared who vowed to lead them back to their former glory — Khyron! — an alien culture’s hero reborn to pick up where Dolza had left off!