On the level Assault on the control room,where it says "If i only had a super weapon", there are two ways to skip part of the level. The first way is to try and get the banshees using the Sortcut technique. The second way is to fall onto the pirimid structure that slopes from the end of the level down. It is best to have full shields while attempting this trick so you don't die. You must aim yourself in the middle of the structure as best as you can. Fall, do not jump, onto the sructure. Right before you hit, crouch to prevent damage. Follow the structure to the bottom into a pit. The pit should contain a rocket launcher and a sniper rifle if you choose to use them. Continue to the top of the structure on foot or with a bonus. The end of the level will still have no enemies. It is harder to do this than it is to get the banshees, that is why it is plan B.