So yeah. I'm this badass nefariously evil dude of awesome power. I control legions of undead that would help me do anything from throwing the world into complete darkness and despair to wiping my frost laden ass after taking a massive shit on my throne. I also have this sweet runeblade that grants the wielder, this mug right here, power eternal. So I'm pretty much the worst imaginable nightmare of all living things and all that, yadda yadda.
But hey, there's one thing I apparently can't do, that would be even more terrifying. NOT. DOING. ANYTHING. And obviously a mind such as my own, capable of deceiving my own enslavers including the creator/destroyer of worlds and his chief lieutenants like they were drunk mormons buying magic beans from a gypsy trailer, couldn't figure out that me being there was actually just a spanner in the works.
I'm Arthas Menethil, but you probably know me better as the most badass antagonist in the franchise turned plot device overnight.