What people don't get is that because the server polls your data every 0.3s, and clearly the time you start doing any raid isn't done with this in mind, sometimes you might just happen to have the server pool your position 0.1s before a WotL ends. In this case the game would behave like any other MMORPG, and you'd dodge WotL quite easily if you're a decent player. Other times, you could get the full 0.3s lag which makes it extremely hard to avoid it. As one of the poster pointed out, try to stop your spell with around 0.3s left by moving, and you'll find that sometimes it works and sometimes it does not, because it's entirely dependent on when the server chooses to query from your client again. You cannot do an action like cancel your spell with any regularity. In fact, you can actually use this to your advantage knowing that your spells will usually still finish despite you moved, so that you get an early start on your movement.