This is only available if youve bought and completed operation anchorage. now if youve got everything you need in the weapon chamber and taken care of the little problem with the traitors go back into the weapon chamber, if you havnt already taken the armor take it and click the bottom of the stand it was on. the floor will open up under you, walk down the stairs and talk to the ghouls on the other side of the door. it dusnt mater wich one, he will thank you for opening the door and tell you to follow him up and he'll explain whats hapnin. when you get up the stairs the general guy will ask you who these guys are. the ghoul will speak and say that they ar in danger. the passage they were in was being used by super mutants and they were gona brake in any moment. the general is shoked but dosnt have time to call for help as you hear the familiar voices of super mutants coming up the stairs, kill all 6 of them and all of you will be called upstairs to find a super mutant behemoth master. this is the one and only strongest creature in the game but luckily youlle have the outcasts help. after killing it there will be another wave of super mutants wich include 3sm masters, 3sm brutes, and 5 normal sm's. after this is over talk to the sargeant and he will say that he found this gun in the chamber and give it to you. if you have the alien gun, you will know that it dusnt kill everything in one shot, but this baby does. its and alien/laser rifle wich is basicly a lazer rifle and an alien blaster stuck together.