This is the Cathedral lair3 section of the map of the wasteland presented by:


Pipboy map:

This is the last level of the cathedral. You should first kill everyone in the main section of this level (don't go in the masters lair). Then search everything and take everything you need and only things you need. Now for the masters part. There are two ways of doing this. The one I prefer is as follows. There is an elevator in the top right hand corner. it and the door in front of it is locked. You will need a high lock pick skill to unlock them both. Once they are both unlocked use the elevator to go to the bomb room, thats right the bomb room, the rest will be explained at he bomb room section. Also there is the face to face with the master way. To do this you will need, a turbo plasma and a gatling laser with lots of ammo and stim pacs. Use the physic nullifier to get past the hallway then get behind the right hand beam. make it so you can use 1 a to go out from the beam and another to go back. wince you are behind the beam, step out and shoot him in the "eyes" with the turbo plasma and step back, also well you are fighting the master mutants will be coming at you and try to pick-off the robots too. Do this till the master is dead then get the hell out of there! Also before you do this make sure that EVERYTHING inside and outside the cathedral are dead so you have no trouble getting out of there.