If you are an admin go into Creative mode and grab the admin blink rifle and switch to destroy mode and enter the overseer arena. Step into the cavity and the overseer should start to form. Wait for about 1 minute. The drones will start to appear and you shoot the overseer with the admin blink rifle that is switched to destroy mode. When the overseer 'dies' There should be another boss.
This boss isn't really that hard. You can go in with assault rifles and riot gear and beat the boss with 7-10 players. Bring a ton of bullets and healing brews because the defense units do a good amount of damage. Rockets will take out the overseer super quick. Also bring fur gear because it gets cold in some parts. 3 sets of everything are a must in fighting the boss and units. Thank you.