This is the game equivalent of the classic movie sequence where someone bends down to pick up his suitcase, and straightens up to see a knife sticking out of the wall. Any attack that your character is not aware of automatically misses. Note that the GM has the final say on what your character is aware of or not; turning around, closing your eyes, and putting your hands over your ears is not going to protect you from the army of abominations you were fighting. This is meant to protect you from deathtraps and sudden ambushes only.
Double or Nothing
Once per fight (or once per scene, if you somehow have a scene without a fight in it) you can do one roll Double or Nothing. Instead of rolling one positive and one negative die, you roll two of each, keeping both. You can’t do this on just any roll, however: It has to be something important and dramatic. For instance, you can’t just do this when you’re trying to sucker punch a couple unnamed punks. But when you’re doing your Flying Windmill Kick at the head bad guy then it’s appropriate. As a rule of thumb, your fellow players should look at you like you’re crazy every time you use this schtick. There is no shot cost for using Double or Nothing.