And I answer myself, perhaps they believed a still greater power could exist, one that could vanquish even Lord Voldemort…. perhaps they now pay allegiance to another …. perhaps that champion of commoners, of Mudbloods and Muggles, Albus Dumbledore?
There are no more uses of "vanquish" in the book.
Show samples from other sources
The team vanquished all competition.
You need to vanquish those negative thoughts and think about good things.