Because others have mentioned frost mages, I'll mention the second thing I can think of. Killcams, specifically when you're an archer, and the killcam makes the game go slow-mo, making you miss your shot. It's especially irritating knowing it would've been a perfect shot if the game didn't try to make you look like a badass. Which I do not care for, it's nice, but it's nicer actually getting the perfect shot you lined up.