Have you ever wondered if it is possible to kill an Elite easily? When you come to an Elite pacing around the room, time how fast he paces by hiding behind a shield or a glass window, stay at a safe distance, or just hide behind a corner. Once you are sure you know when he will turn around, run up behind him and use the melee attack to bash the Elite on the back, instantly klling him (note that if you did not do it correctly, it will turn around and attack you). This comes in handy alot on "Attack on the Control Room" and on Legendary Difficulty.