Mass Fusion

Fallout 4 guide · securing the Beryllium Agitator

The Mass Fusion building is an advanced research skyscraper where the player must secure the Beryllium Agitator from the high-radiation reactor core on the lowest level. Depending on whether you align with The Institute or the Brotherhood of Steel, you will fight through waves of opposing faction soldiers while descending the facility. Starting this quest permanently hostilely aligns you against whichever of those two factions you choose to oppose.

Don't miss 0/1

Freefall Legs (Left and Right): In a locked safe in a high office accessible only via jetpack or glitching above the upper floors

Items

0/4

Beryllium Agitator: Inside the reactor core chamber at the base of the facilityMass Fusion Executive Lab Keycard: In an executive desk on the upper office floor next to a terminalScience Bobblehead: Resting on the edge of the large circular desk structure on the upper mezzanine office levelTesla Science Magazine: On a computer console table on the upper office level

Secrets

0/1

The Freefall Legs armor pieces are hidden in a locked safe on an isolated top-level room that has no stairs or elevator access; reaching them requires a power armor Jet Pack or carefully climbing wall fixtures.

Enemies

Sentry Bot

Weak to Combat InhibitorSteal / drop Fusion Cores

Deploys on the ground floor lobby to intercept the player.

Assaultron

Weak to Combat Inhibitor

Attacks aggressively with a head laser beam and melee charges in the lower lab corridors.

Turret

Weak to Combat Inhibitor

Automated ceiling and wall turrets guarding the reactor chamber and hallways.

Tips

Entering the reactor chamber exposes you to lethal levels of radiation, so equip a Hazmat Suit or Power Armor before unlocking the decontamination airlock.
Pressing the airlock decontamination button will automatically trigger the facility security alert, causing high-level robots to attack once you exit the chamber.
Restoring power to the glass elevator via the circuit breaker allows a faster descent, but you can also fight your way down via emergency stairwells if the elevator gets disabled.

Not listed for this area: shops and people.

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Quincy

Vault 81

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