Twilight has always been the best there is at magic. She's won dozens of scholarly competitions and tests of skill in Canterlot. But when it comes to the more violent uses for magic, she is essentially clueless.
When she meets a strange unicorn in a seedy bar, he introduces her to a little known sport that will test her knowledge of magic in different ways. That is, of course, if Twilight can't resist its primal lure.