There are several subsequent versions of this book. This one is "vintage" published in August 1978, and contains three books: "The Bull and the Spear","The Oak and the Ram", and "The Sword and the Stallion."
This volume collects the second trilogy in the saga of Corum Jhaelen Irsei and consists of "The Bull and the Spear", "The Oak and the Ram", and "The Sword and the Stallion". Corum, for those of you who are not familiar with Moorcock, is an incarnation of the Eternal Champion. In this trilogy, Corum is called into the distant future to assist in the battle against the Fhoi Myore. While there, he learns some important lessons about love and belonging.
Moorcock returns to the world of the Eternal Champion, in the guise of Corum, then rips him out of it. Over a thousand years after the events of the last novels, Corum has become worshipped as a demigod. His followers summon him into their time to do battle with extraplanar beings of (at most) animal intelligence known as the Cold Gods. The Cold Gods are dying, slowly, but they have every intention of taking all of humanity with them.
Together with the last of the Sidhi, a race of magic-using nonhumans roughly akin to elves in most fantasy worlds, Corum and those who worship him go to do battle with another force bent on destroying the planet.