Mass Effect 3 Arrae Ex-Cerberus Scientists Guide (PS3)

Mass Effect 3’s Arrae: Ex-Cerberus Scientists is a side mission centered on tracking down Cerberus defectors and surviving a series of escalating fights. This guide walks you through where to find every loot item, how to handle each combat phase, and which dialogue choices can swing your morality score.

Task Search

This wiki-style page focuses on the Arrae: Ex-Cerberus Scientists side job, covering item locations, survival tips for every encounter, and the decisions you’ll make along the way.

If you’re looking for something specific, you can jump straight to the sections below: Mission Stats; Talk to Specialist Traynor; Travel to Arrae; Defend Scientists; Locate Survivors; Locate Brynn; Reach the Satellite Console; Activate AA Guns; Reach the Landing Pad; and Back on the Normandy.

Mission Stats

Video Guide

Mission Rewards

Mission Experience: 2,000 XP
Reputation: +15 Reputation
Mission Credits: 12,500 credits
Found Credits: 12,500 credits
Weapon: M-6 Carnifex
Armor: Kassa Fabrication Greaves
Mods:
- Assault Rifle Magazine Upgrade
- Shotgun High Caliber Barrel
- Shotgun Spare Ammo
- SMG High Caliber Barrel
War Assets:
- Ex-Cerberus Scientists (25 TMS)
- Dr. Brynn Cole (25 TMS)
- Tap to Reveal (25 TMS)
- Tap to Reveal (25 TMS)

Assault Rifle Magazine Upgrade
Shotgun High Caliber Barrel
Shotgun Spare Ammo
SMG High Caliber Barrel

Ex-Cerberus Scientists (25 TMS)
Dr. Brynn Cole (25 TMS)
Tap to Reveal (25 TMS)
Tap to Reveal (25 TMS)

Mission Enemies

Assault Trooper
Guardian
Centurion
Combat Engineer
Turret
Phantom
Atlas Mech

Talk to Specialist Traynor

Prerequisite: Complete “Priority: The Citadel 2”

This side mission won’t show up until you’ve finished “Priority: The Citadel 2”. Once it’s available, return to the CIC. Specialist Traynor will flag Shepard again with urgent information: Cerberus’ leading scientists have reportedly severed ties, and Traynor believes she knows where they’ve gone to ground.

Travel to Arrae

Location: Minos Wasteland – Arrae – Gellix

Start by heading to the Minos Wasteland near the “western” edge of the Milky Way, then move west to the Arrae system. Land on the planet Gellix (shown in green) to begin the mission.

While you’re in Fortis and working through the Relay hub, it’s a good time to grab the Search and Rescue items available in this area.

Recommended Loadout

Squad Tactics:
- Garrus is a strong choice because his Overload and Proximity Mine abilities help you break through defenses, and his sniper rifle is ideal for long sight lines.
- James is also a dependable option thanks to Incendiary Ammo and his Frag Grenade powers.
- If you delay this side mission until after “Priority: Rannoch”, Tali becomes especially useful since she can sabotage Generators and Shield Pylons here; her Energy Drain helps set up Tech Bursts.
Unique Dialogue:
- Garrus and EDI offer the most distinctive dialogue during this run.
Shepard’s Loadout:
- Using Piercing, Shredder, or High Velocity mods, along with the Venom Shotgun, will make short work of the Guardians you’ll face.
- The Sniper Rifle Enhanced Scope is particularly helpful because Centurions and Atlas mechs rely on smoke bombs that can hide targets at key moments.
- If you own the Citadel DLC and/or finished the Omega DLC, a Thermal Scope for your assault or sniper rifle helps you see through smoke bombs and even through walls.

Garrus is a good choice for this Mission because of his Overload and Proximity Mine abilities, and his sniper rifle is great for his level’s long sight lines.
James is another solid pick for his Incendiary Ammo and Frag Grenade powers.
If you save this Side Mission until after “Priority: Rannoch”, Tali is a great choice because she can Sabotage the Generators and Shield Pylons in this level, and her Energy Drain is useful for setting up Tech Bursts.

Garrus and EDI provide the most unique dialogue for this level.

Piercing, Shredder or High Velocity mods, as well as the Venom Shotgun, will help deal with this level’s Guardians.
The Sniper Rifle Enhanced Scope is very helpful for seeing through the smoke bombs used by Centurions and Atlas mechs.
If you have the Citadel DLC and / or completed the Omega DLC, a Thermal Scope for your assault / sniper rifle helps see through both their smoke bombs and through walls!

Defend Scientists

As soon as the fight begins, you’ll be stepping into an active firefight between the refugees (including a familiar presence if he made it through Mass Effect 2) and Cerberus forces. The enemy is protected by Shield Pylons—two of them—that bolster the personnel under cover, so prioritize destroying those whenever you get the chance.

More attackers drop in from above using jet boots. That descent exposes them broadly, leaving them wide open to sustained gunfire—so don’t waste the advantage.

Locate Survivors

Once the Cerberus troops are cleared out, locate the man shown in an earlier cutscene behind crate cover. Shepard will pick up a communicator and connect with Dr. Brynn Cole. From there, the scene can go one of two ways:

If Jacob Taylor survived Mass Effect 2, he’ll be on-site and vouch for Shepard, which convinces Dr. Brynn to open the door inside.
If Jacob died at the end of Mass Effect 2, you’ll instead have Dr. Webber—too badly hurt to do more than sit through the moment. Dr. Brynn won’t trust Shepard, and three additional Cerberus troops arrive. After you eliminate them, Brynn finally accepts what’s going on and opens the door.

Now you’ll speak with Dr. Brynn Cole directly. If Jacob is present, he insists he’s fine, though he still clearly needs attention. This is also where you can earn Morality Points:

Select “Running was smart” to gain +2 Paragon Points.
Select “Running took guts” to gain +2 Renegade Points.

After EDI comments, you can explore the base. Turn right first to spot Dr. Brown on the floor speaking with another refugee. When they’re done, talk to Dr. Brown for +2 Reputation.

Locate Brynn

From there, go up the nearby stairs toward a door ahead. To the right of that door, working at a terminal, is Dr. Gavin Archer. If you completed the Overlord DLC in Mass Effect 2, Shepard won’t react well to seeing him again. The mission also has a grim possibility: Gavin can tragically die by the end of this cutscene depending on your choices.

Dr. Gavin Archer takes his own life if any of the following are true:
- You did not finish “Grissom Academy: Emergency Evacuation” before “Priority: The Citadel 2”, so that quest has expired.
- You DID complete “Grissom Academy: Emergency Evacuation”, but you refused to tell Gavin what happened to his brother by choosing “[Let him worry]”.
- You never sent David to Grissom Academy at the conclusion of the Overlord DLC (or you never completed Overlord), and then you resolved “Priority: Rannoch” peacefully before starting this side mission.
In any other situation, Dr. Gavin Archer survives.
If you did complete Overlord and Gavin lives through the cutscene, he becomes a War Asset worth 25 TMS.

You did not complete “Grissom Academy: Emergency Evacuation” before “Priority: The Citadel 2”, causing it to expire.
You DID complete “Grissom Academy: Emergency Evacuation”, but refuse to tell Gavin the fate of his brother by choosing “[Let him worry]”.
You didn’t send David to Grissom Academy at the end of the Overlord DLC (or never did the Overlord DLC at all), then negotiated a peaceful resolution to “Priority: Rannoch” before starting this Side Mission.

When the cutscene ends, start combing the base for equipment:

Datapad – 2,500 credits. On a table just past Gavin’s terminal.
Datapad – On a table beyond the previous datapad. This one provides lore.
Assault Rifle Magazine Upgrade – Go through the door beside Gavin’s terminal, then look to the right of the Weapon Bench ahead to find the mod.
Medical Station – 25 XP. Climb the next staircase, enter the door, and check the right side of the next stairs for the station.

At the top of the stairs, you’ll reunite with Brynn. Shepard learns that not only are the ex-Cerberus scientists here, but their families are too. Cerberus, as usual, is vengeful. You can then say:

“There’s a lot on the line” for +2 Paragon Points.
“We can’t let that distract us” for +2 Renegade Points.

Reach the Satellite Console

After another talk with Jacob (assuming he’s still alive and present), your next objective is to reach the roof—though first, it’s worth squeezing in more conversations and loot. Start by speaking with Brynn nearby to learn about available topics, then head out for items.

Datapad – 2,500 credits. Located on a science station to the left of Dr. Brynn.
Datapad – To the left of the datapad described above. Provides additional lore.

From the second datapad, move along the left wall until you find a doorway into a “Recovery-2” room, where the next batch of goodies is waiting:

Kassa Fabrication Greaves – Stand in the “Recovery-2” doorway and look right. The armor piece sits in the corner above some crates.
Medical Station – 75 XP. It’s to the left of the “Recovery-2” doorway.
Datapad – 1,250 credits. Found on a table in the middle-left of the room, close to Jacob if he’s present.
Datapad – On a bed in the back-left corner. This one also provides lore.

If Jacob is present, you can talk to him now and catch up on what he’s been doing since Mass Effect 2. After choosing an “Investigate” topic, selecting “Tell me about Dr. Cole” leads to interesting revelations—especially if you Romanced Jacob in Mass Effect 2.

Once you’ve finished in “Recovery-2,” leave the room to pick up the final loot items:

Datapad – Straight ahead on crates at the top of the stairs. Provides lore.
Turian Toxin Data – From the datapad above, head to the back-right corner to find a microscope among crates. Examine it to obtain the quest item for “Citadel: Cerberus Turian Poison”.
Shotgun High Caliber Barrel – Return to the “Recovery-2” doorway, face the stairs, and turn right toward the exit door. Before you go through, check behind the crates on the left side of the door to find this weapon mod.

After confirming you’ve grabbed everything, exit through the door where the shotgun mod was located. Turn right and climb the ladder; you’ll transition through a loading screen. At the top, check the pipes on the left wall to find the Heavy Pistol: the M-6 Carnifex.

M-6 Carnifex

The M-6 Carnifex returns from Mass Effect 2, acting like a beefier counterpart to the M-3 Predator. It hits harder, but you trade away fire rate, ammunition efficiency, and weight—while keeping impressive accuracy.

When you arrive, Cerberus has already taken over the roof. The first group hasn’t spotted you yet, so open with surprise. Make sure you remove the Shield Pylon first, since it strengthens defenses for anyone nearby. After that, kill the Combat Engineer before he can plant a Turret and make the fight even more punishing.

Move up the ramp at the back and angle right to find a lone Combat Engineer at the Telemetry Override. Eliminate him, then clear every Cerberus Trooper that drops from above—again, their fall leaves them very exposed. With the roof briefly quiet, you can loot without immediate pressure:

SMG High Caliber Barrel – At the entrance to the side area containing the Telemetry Override, there’s a pile of crates. Check behind them to find the mod.
Datapad – 2,500 credits. On the ground to the right of the telemetry controls.
Med Kit – 50 XP. Hidden in the shadows behind the datapad listed above.

KBABZ Tip

Until you activate the Telemetry Override, the rooftop stays empty, making it one of the best windows to farm loot. Destroying four Generators will disable the Shield Pylons, so this is also your chance to weaken the enemy’s defensive setup.

Now sweep the rest of the rooftop for remaining items—without enemies firing at you, it’s noticeably easier:

Med Kit – 50 XP. Face away from the Telemetry Override and climb to the roof’s back level. You’ll find a med kit on your left sitting on top of ducting.
Sniper Rifle Piercing Mod – From the med kit above, go to the railing at the very back of the roof. Turn right to spot the mod among a large cube container.
Datapad – 3,750 credits. Starting from the Piercing Mod, use the ladders on the left side of the roof to reach the highest point. Head left and move forward until you mantle onto a ledge. The datapad sits ahead on ducting near the AA Guns.
Med Kit – 50 XP. Under the ducting where the datapad above is located.
Shotgun Spare Ammo – From the datapad and med kit you just collected, find the nearby ladder and slide down. Before you slide down the second ladder, check the small area for this last mod.

Activate AA Guns

With the loot sweep complete, return to the Telemetry Override and activate it to continue the side mission. The next move is to manually bring the anti-aircraft weapons back online. They’re positioned far away, and your push will be interrupted by a wave of hostiles, including one firing from a mounted turret in the distance.

Take cover and creep toward the turret. Your approach should focus on the left-hand structure, which has ladders that lead up to the AA Guns. Once you reach the shaded back section of the rooftop, you’ll be safer.

At the AA control point, assign squadmates to handle repairs. If possible, leave behind someone who’s strong and comfortable with sniper rifles—so if you brought Garrus, don’t make him the one repairing the AA Gun.

While the other squadmate works on the repairs, climb onto the turret and start shooting down Cerberus forces arriving from dropships. If your turret aim is solid, the enemies should be manageable, but make sure you prioritize any Phantoms—particularly those dropping onto the same elevated rooftop you’re on.

Reach the Landing Pad

When the AA guns are operational and the repairs are finished, you’ll go back inside to Dr. Brynn (and Jacob, if he’s present). If you missed any items on the upper floors, you can select “Not yet” to retrieve them; doing so won’t change the mission’s end state. Otherwise, choose “Evacuate immediately” to trigger the final portion of the mission.

Evacuation doesn’t come easy. Cerberus troops begin to pour into the facility, so you’ll have to fight your way back out to the landing bay where Cortez originally dropped you off. Hold the line as you defend the departing shuttles.

This is also your final chance to grab the Turian Toxin Data. If you skip it here, you’ll need to purchase a similar item from Spectre Requisitions on the Citadel in order to complete “Citadel: Cerberus Turian Poison”.

The outdoor combat turns intense quickly. Start by destroying the Generators so the Shield Pylons stop functioning. Unfortunately, the shuttles now deploy troops at higher elevations, which means you can’t simply delete them with the usual tactics. Just as you think things are over, an Atlas Mech arrives, supported by a Combat Engineer. The engineer repairs the mech and sets up Turrets, so stay behind cover and hunker down.

After wiping out every enemy on-site, you’ll be automatically extracted by Brynn. If Jacob is present, you’ll also get an opportunity to earn Morality Points:

Choose “I understand” for +2 Paragon Points.
Choose “I’m disappointed” for +2 Renegade Points.

Back on the Normandy

Once the mission wraps, you’ll receive a debriefing with Admiral Hackett, then you can take another pass through the Normandy.

CIC – Talk with Traynor, Joker, and EDI. Also check your email: you’ll have messages that include requests from your Virmire Survivor, Miranda, Joker, Garrus, Liara, and Javik.
Crew Deck – Listen to James and Garrus in the mess hall. You’ll need to walk between parts to hear all three segments before talking to Garrus. Then visit Liara and her Broker Terminal. You can also speak with your Virmire Survivor: Ashley will be in the Port Observatory, while Kaidan is in the Crew Quarters (with +2 Reputation granted only for Kaidan).
Engineering – Chat with Javik and Allers.
Shuttle Bay – Talk to Cortez for a brief comment.

If you want more Mass Effect 3 help, the guide page also points you toward additional sections including Legendary Edition changes, how-to guides, key choices and consequences, romance guidance, walkthroughs, and side missions.

Mass Effect 3 Arrae: Ex-Cerberus Scientists Guide—Loot, Combat & Morality

Task Search