Anyway, first of all, what you need to do, is get a teammate either on split screen or online, and then go to the Blue base and behind right at top, should be a ledge where you can stand on, I'd say take a Banshee up their
Anyway, next get someone to stand on top of you or you stand on top of someone, then make them bump you all the way up, in other words Sword Cancle you up, then the person underneath has to move right out of the way while you fall down, so the person on top doesn't touch te person underneath, now, it's easy, as soon as you land on the ledge again, just walk straight up into the invisible wall and you will go through it, Note that you wont be able to if you didn't Sword Cacnle like 3 meters off the ledge, or if you touched the other teammate, but you have to be NOT on teams, other wise it wont work, anyway now the person underneathe can walk straight through too. Enjoy.
http://files.mythica.org/halo/highimpac ... arrier.avi
