There are a few things to keep in mind when it comes to AoE attacks. First, the cast bar is what determines when things get hit, NOT the animation. So if you're still inside the circle when the bar finishes, you're getting hit, even if an attack takes a bit to launch from the boss. Second, there are network issues to consider: What matters is where the SERVER has you placed, not where your computer has you placed. For most users, this delay is barely more than a third of a second, so it only matters if you escaped RIGHT as the attack went off. If your internet connection is horrendously bad however, that can make things more difficult.