I hereby nominate this level for Coolest Name In This Game :P
This chapter is the turning point of Marathon 2, when the story goes off in an entirely new direction. Tycho has won, and Durandal has just a short time to ensure that his plans will succeed even after his death.
This level is pretty light on story; what it gives is action. One of the three hardest levels in the series, as chosen by Frigidman for Marathon Infinity, it is a dangerous environment loaded with swarms of monsters: Troopers, Hunters, and our old friends the Assimilated Civilians. Frog blast the vent core! :P
There are a few alternate routes through this linear level. It is possible at several points to grenade hop onto the ledges the monsters are pouring out of, granting access to the entire level without having to open the blast doors. This also makes getting the rocket launcher and making somebody pay easier. Near that rocket launcher, a staircase at the bottom of the Pfhor slime leads up to another ambush ledge.
