The Immortal of World's End (Gondwane Epic)

the long version

Ganelon Silvermane, the genetically designed superhero of the Earth's fabulous final age, has rapidly become the most popular of all Lin Carter’s creations. Brought to life prematurely, Ganelon’s adventures in a world of crumbling empires, ravaging hordes, and marvelous relics of forgotten scientific empires are always edge-of-the-seat wonder novels. In his third adventure, Ganelon Silvermane encounters a city of illusion, the problem of scientific immortals, and the disastrous collision of a massive horde of the world's ultimate barbarians!