Another re-read as I work my way slowly, with so much enjoyment, back through this very favourite series.
From the Blurb:
When last seen, the singularly inept wizard Rincewind had fallen off the edge of the world. Now magically, he's turned up again, and this time he's brought the Luggage.
But that's not all....
Once upon a time, there was an eighth son of an eighth son who was, of course, a wizard. As if that wasn't complicated enough, said wizard then had seven sons. And then he had an eighth son -- a wizard squared (that's all the math, really). Who of course, was a source of magic -- a sorcerer.
All this books and stuff, that isn't what it should all be about. What we need is real wizardry.
All is not well within the Unseen University. The endemic politics of the place have ensured that it has finally got what it wished for: the most powerful wizard on the disc. Which could mean that the death of all wizardry is at hand. And the world is going to end, depending on whom you listen to. Unless of course one inept wizard can take the University's most precious artefact, the very embodiment of magic itself, and deliver it halfway across the disc to safety...