Updated Title Publisher
Updated Title Publisher
Updated Title
Published Title Score Editor's Choice
Published Title Score

Fallout 4

Mass Fusion

Nathan Garvin
Important Items in This Area
Tesla Science

The Institute

Go ahead and talk to Allie Filmore, who is waiting by the elevator for you. She will tell you that you need to go up to the surface and obtain a Beryllium Agitator, from the ruins of "Mass Fusion" iconMass Fusion. Should be fun, right? She isn’t too happy to do it, but she is coming along and tells you to meet her by the relay. Use the elevator now and head to the relay, where you can interact with it and be given the following warning:

“WARNING: Relaying to Mass Fusion will make you a permanent enemy of the Brotherhood of Steel. Are you sure you wish to proceed?”

This is a point of no return, as you may have guessed, but it’s a decision you should have made a while ago now as far as factions are concerned.

Mass Fusion Executive Suite

Thanks to the Relay Device, you will warp to the top of the Mass Fusion building, discovering the “Mass Fusion Executive Suite”. You aren’t the first here though, the Brotherhood is already here and as you know they are now are enemy. Inside the building are a number of Scribes and outside is a Knight in Power Armor, so focus on him and let Allie distract enemies while you wipe them out. (Note that she is essential and therefore can’t be killed, which means you don’t have to worry about babysitting her).

Once you can, head in and up the stairs. You can head all the way up to a third level to find a door [Advanced] you can pick for a First Aid Box and goodies, as well as an outside area you can search for another First Aid Box. Head back down to the second level and across the way to see the Beryllium Agitator is not here, meaning you’ll have to go search the building. You can find the “Oslow’s Office Recording” holotape here. Give it a listen and then hack the terminal [Advanced]. Read the first email here to learn the Beryllium Agitator is in a reactor and you need the “Executive Keycard”. Lovely. Thankfully enough, just leave this room and check the desk nearby for the “Mass Fusion Executive Lab Password” and the “Mass Fusion Executive ID”. That was very easy! Use the keycard on the middle elevator here to proceed into the Mass Fusion building proper.

Mass Fusion

As you head down the elevator, you will be ambushed by Brotherhood soldiers. Use VATS to kill them on your way down and go into sneak mode to reduce your profile. Kill as many enemies as they pop up, focusing on the doors to the left and right as you go down. When you do hit the floor, a Knight in Power Armor will show up with Scribes coming in from the left and right. Take them down and, once you are free to explore, head into the north room to find the “Mass Fusion Labs Key” on the table. There is also a manager’s terminal here that you can unlock with [Expert] hacking skills. This will allow you to re-route the power and completes the optional “Restore Power” objective. Also, be sure to head east from the glass floor, hanging a right and going forward until you find a ramp. Take that up and out to a destroyed balcony. Head right hugging the wall and you will wrap around to a room with a blue console you can wearch for a copy of Tesla Science . Barring that, you can head to the northeast corner to find an [Expert] locked door (or, with the key you picked up, a door you can open automatically) that leads downward. Do one of these things to allow us to continue heading downward.

From the lower floor, head up the left steps and into the left door to see an elevator with a key card reader. You can of course use this now, so enter in and head down. Once you get off, Allie will point out the reactor, which you can see past the window. Before you head that way though, head through the south door to find the “Prototype Lab Terminal” with a lock [Novice]. Hack it and turn on a Protectron unit here, then go ahead and kill it. After that, go ahead and take the north door down to another office area. Here there is an “Attendant’s Terminal” [Advanced] you can hack to get several options.

Back out and save now, as you are about to let some enemies attack you. If you are handy with explosives, you can mine the two doors across from the terminal if you wish. Once you are ready, use the terminal to activate the Assaultron Units. This will make two of them come out of the doors so take them out. You are doing this so they don’t get to choose when to attack you, by the way. Next up is the turrets. Activate those as well and shoot down the one above the terminal and the one in the southern room. This locker room to the south mostly has junk, but the bathrooms beyond have a First Aid Box you can loot.

Head back and into the reactor-viewing area. There are some balconies to the left and right and, at the end of the left one, a Steamer Trunk. Go ahead and loot it then note the mag-lock doors on each balcony. Yes, this facility is going to ambush you with these (lovely). Also note the area underneath the stairs, which has a hallway (which is odd) and doors with rooms off to the side. One of them has a locked “Analyst’s Terminal” [Novice] and a locked safe [Master]. You can unlock the safe with the terminal if you wish, but be sure to free the Protectron and kill it off like you did before.

OK, you are done with enemy prep work. All that is left is getting the Beryllium Agitator. You have to go into the reactor to do that that, and it is very radioactive, so if you don’t have your own Hazmat Suit, go to the locker room and get one from there. Put it on and then make your way to the decon room. Hit the button and enter the reactor. Make your way up to the reactor and hit the button, which will allow you to pick up the Beryllium Agitator.

Doing this sets off the security system. What you need to do right now is shoot the two Laser Turrets up on the ceiling to the west. Take them both out and you’ll be safe, then head back to the decontamination room. Hit the button and then put back on your regular armor. Inside the viewing area is one more Laser Turret up on the ceiling and finally a Sentry Bot that comes in out of the north door. Chuck some explosives up there to soften him up and then take him on as he comes out. If it focuses on your AI teammates, lay into it like normal but you can also use the hallway under the stairs to take cover. Just beware of the explosion once it dies.

You now have to leave the building, so head east up the stairs and use your key card to open the door. Take the elevator back up and you’ll hear the Brotherhood is still fighting. Once you get out, help the Institute Synths clear out the Brotherhood soldiers in the lobby for the XP, then exit the building. Warp back to "The Institute" iconThe Institute once you’ve left the building. Once here head to Advanced Systems and speak to Allie. She will take over from here as this quest officially comes to an end. Wait for a bit and the next Main Quest, "Pinned" iconPinned , soon begins. Another side-quest, "A House Divided" iconA House Divided also begins now. Might as well take care of that, first.

Objective Reward
For obtaining the Beryllium Agitator 708 XP
No Comments
Guide Information
  • Publisher
    Bethesda Softworks
  • Platforms,
    PC, PS4, XB One
  • Genre
  • Guide Release
    16 December 2015
  • Last Updated
    11 May 2024
    Version History
  • Guide Author
    Nathan Garvin, Greg Wright

Share this free guide:

It’s just another day. Having just been accepted into Vault 111, you spend the morning with your family going about your daily routine. That is until alarms blare out, signalling a nuclear attack. You and your family sprint towards the Vault along with everyone else in the neighborhood just as a bomb explodes nearby. After surviving the blast, you are lowered into the Vault and enter cryosleep. Two hundred years pass and you awake to a world ravaged by nuclear war. You are the Sole Survivor and what awaits you is a mystery as you set out to conquer the Wasteland.

Our guide will be a complete companion while you journey through the wilds of Fallout 4. You can find a plethora of information including the following:

  • A start to finish walkthrough with every area in between covered.
  • Combat details, SPECIAL explanation and general gameplay information.
  • VATS And You!: Getting to know your PIPBOY.
  • All faction quests explained including the consequences of favoring one over the others.
  • Information on Settlements and items for construction.
  • Bobblehead locations, collectibles and full Trophy/Achievement guide.
  • Settlement Guide complete with how to set up and manage settlements, what perks are beneficial etc.
  • Companion chapter detailing each companion character, where to acquire them and the pros/cons of each.
  • A detailed Character Creation guide fully examining the best builds and what each perk does.
  • Automatron and Wasteland Workshop DLC information provided, including a full walkthrough for Automatron.
  • A complete walkthrough of the “Far Harbor” DLC complete with information on every side quest.

Get a Gamer Guides Premium account: