The young sourcerer Coin creates a gigantic thaumaturgical tower out of pure condensed magic and doesn't even break a sweat, then he goes on to capture the gods inside a magical marble, all with a single gesture.
Not to forget, in the same book, he tries the same thing with the sourcerer Coin who, just before, trapped the gods in a glass ball without even breathing hard.
"It sort of kills people but leaves buildings standing."
Earlier, Rincewind gets a cut on the side of his head from a thrown knife and faints at the sight of his own blood. Later, he get whacked across the head with a sentient staff made of metal, which very likely may have caused an even greater injury, and simply gets back up and keeps fighting. Wow. Maybe he only faints at the sight of blood and is alright otherwise or it could be a subtly awesome form of Character Development.
The wizards decide they're going to burn all the books in the library, so they sneak in at night, it's dark, one of them lights one match, and "the Librarian dropped on him like the descent of Man". Also Funny Moment because of the superb phrasing.
You have to give points to the Archchancellor's Hat (possessing Abrim) for easily obliterating even sourcery-empowered wizards.