The Broken Lands - Fred Saberhagen

I'm sure I've encountered 'the magic comes back (or is revealed)' after some catastrophe many times before, but the only one I can think of at the moment is Stephen King's The Stand. Though it's not stated I would guess, going by the time this was written, the catastrophe here would have been nuclear war. So technology is lying around, sorcerers raise elementals, and agents of the evil empire of the East are enslaving the good farming folk of the West. A boy whose parents are killed is set on a course of vengeance and joins the revolution . . . and thus far it is all pedestrian and predictable. But the Eastern ruler fears the elephant, for it has been foretold to bring him down and now, to throw a SPOILER in: it doesn't have legs but treads and runs on nuclear power. I didn't enjoy this as I remembered. I think that's more to do with my mood and wanting to get onto what I remembered as the good stuff. New readers may well enjoy it a lot more because, being pretty much fantasy, it's not really gone past its use by date.