I need an understanding of line of site checks because I can look directly at an enemy and not be able to use a skill. What i`m guessing is that there is a delay for the game to make sure your on target? If so then that would explain alot of what is going on in the game, take for example single target abilities are from point A to point B direct damage but AOE damage is from point A to point area A target. If that is correct then that is why an AOE skill will work 100% of the time compared to a single target skill. So if there is a check then we need a better understanding of how and why it works.