This post is all spoilers and walkthroughs for Marathon Eternal for Aleph One. For the Level list, see http://traxus.bungie.org/index.php/Eternal_Volunteers
This is a hard and sometimes aggravating level. You can't kill all the enemy, they just regenerate. However, that means that you must use new skills. Draw them all off one way, then race the other to explore it. I'm not sure where they regenerate, but you can temporarily clear them out of a limited area. They must regenerate, then travel to where you are.
To leave this level, jump into the two big red lung shapes on the map, hit the switch, and begin the elevator ride up. But don't do this till you are fully charged because aliens will just rain on you. Also, make sure you have obtained those fantastic swords and all the ammo you can find. Both will appear as white dots on the map.
The only thing that can kill the wraiths is the N-cannon or the blades. Both take the zero point nodules as ammo. You can use one blade in each hand. The blades use ammo very slowly, and one swing clears out anything within a radius about double the Phfor staff's radius. Watch out because the flying balls cause destruction within a short range when they die.
There is a save terminal in an enclosed room that looks like a doughnut on the map. But the enemy can operate the doors. There are chargers upstairs. The blades are upstairs in an enclosed room.
If you survive the ride up the very slow and large elevator, head left and go into the first door you find. Once you get it closed, they pretty much leave you alone. There is a saver and a charger there and from there, you teleport to the next level.
