There is no "ambiguity" with aoe in this game and if you haven't figured it out how aoes work in this game, you aren't very observant. The aoe you have to move away is from the cone/circle. As soon as the enemy is done casting, it makes the red go away. As soon as the red is gone, you can go back to where you were regardless of if the animation has gone off or not. So in other words, you have the time it takes for the enemy to finish the cast and NOT the time it takes for the animation to go off.