This was a very foolish thing to do, because Xel pulls his staff (the willow one he made almost a year ago) out of his astral pocket and cuts Rincewind's knees out from under him, hard. He slams the pointy end down between his legs when he falls, piercing his robes and pinning him to the ground. Even though it's asphalt. It's not easy for someone of Xel's height to loom, but he manages it. "Let's try that again," he says in a very, very quiet voice, "this time without the bit where you insult my Lord Mother."