Phoenix in Obsidian

Blurb

Phoenix in Obsidian is a science fantasy novel by Michael Moorcock. First published in 1970, it is the second book in a series that follows the adventures of the Eternal Champion as he is flung from one existence to another. The first book in the series, The Eternal Champion, told the story of John Daker, an average 20th-century man who suddenly found himself incarnated as Erekosë, a legendary hero of Earth in the distant past. He had been called to lead humanity against its Eldren foes, but ended up taking the Eldren's side. Phoenix in Obsidian continues the story, which is concluded in The Dragon in the Sword. The trilogy is part of a larger cycle about the Eternal Champion as defender of the Multiverse.
Having resolved the human-Eldren war, Erekosë finds himself once again called to a strange world to defend Earth from invaders. This time he is Count Urlik Skarsol, Lord of the Frozen Keep, sleeping hero of a frozen and dying Earth. At Rowernarc, the Obsidian City, he hears of the Silver Warriors from the Moon, which long ago crashed into the other side of the Earth.