Sourcery

There was an eighth son of an eighth son. He was, quite naturally, a wizard. And there it should have ended. However (for reasons we'd better not go into), he had seven sons. And then he had an eighth son ... a wizard squared ... a source of magic ... a Sourcerer.

SOURCERY SEES THE RETURN OF RINCEWIND AND THE LUGGAGE AS THE DISCWORLD FACES ITS GREATEST -AND FUNNIEST- CHALLENGE YET.