Lack Of Vision is one of the thirteen network levels in Marathon 2: Durandal.
There is a 2x health charger at the top of the elevator. (Shown on the map as a blue circle with a 2x beside it) Before going to get the 2x health I would suggest getting the super sheild nearby. To activate the elevator shoot one of the switches on either side with a cherged fusion pistol or a grenade. The elevator will start rising. (Make sure you're on it at this point) Be careful no one is near or they will stop you rising by shooting one of the switches again, or will just kill you.
Marathon 2: Durandal - Network Level: Lack Of Vision