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Arrae: Ex-Cerberus Scientists

Claire Farnworth

The planet Gellix (left) is where the mission takes place. The Cerberus suit (right) is a great purchase for snipers.

This mission’s location is in the Arrae solar system on the planet Gellix . You’ll be landing in a hot-zone with plenty of Cerberus troops just around the corner (after you deal with the two Assault Troopers that try to crash your entrance). Take cover at the top of the stairs, destroy any shield generators first and then focus on finishing off the Cerberus troops. Now walk around the side of the crates near the door and speak to a face familiar to Mass Effect fans…

Inside the Facility

Once you’re inside, talk to the people to your right for an easy +2 Reputation Points. Now run up the stairs, run to the end where the tables are and scan the datapad for 2,500 Credits . You can speak to the doctor by the door or just go inside to the next room.

In here there’s a weapons mod bench and an Assault Rifle Magazine Upgrade mod laying on the floor right beside the bench. Head up the stairs, open the door and scan the Medical Station for XP (and any gel if needed).

After the cutscene upstairs, look to the left of Dr. Brynn and on the table you’ll find a datapad worth 2,500 Credits . Nip into the medical bay on your right (where Jacob is), and pick up the Kassa Fabrication Greaves armour upgrade from the crates on your right. There’s also a datapad in front of Jacob (on a table top) worth 1,250 Credits .

There’s a Medical Station on the wall opposite Jacob worth XP. Outside - opposite the top of the stairs - there’s a microscope that contains Turian Toxin Data (required to complete the side mission Citadel: Cerebus Turian Poison ), so be sure to pick that up. Finally, just before you enter the doors into the dark corridor leading to the roof, look on the ground by the scientists for a Shotgun High Calibre Barrel mod.

The Turian Toxin Data is needed for another Citadel side mission (left). Climb the ladder and grab the Carnifex (right) on the left.

Rooftop Shootout

Climb the ladder to the roof and on a metal steam pipe to your left, pick up the powerful M-6 Carnifex pistol; also if you have any armour-damaging ammo-enhancers, equipping them now would be a good idea.

Your best bet here is to destroy the shield generator in the middle as it’ll make killing the Engineer and other guards much easier for you.

Kill the Engineer first, then the Centurion and finally finishing off with the Assault Troopers. When you look over the lip of the ramp, don’t be surprised if you see an Engineer standing still with his back turned to you. This is a glitch as he cannot be destroyed until he’s become active (believe us, we’ve tried)!

However, if you look for the flashing ammo crate to your left, you can take cover here and collect the SMG High Calibre Barrel while you’re stocking up on ammo. Multiple troops will now drop in, so get your team behind cover and get a grenade in there as the area is small so the blast damage will soften quite a few of them up for you.

When it’s clear, walk up to the Telemetry Override and pick up the Medi-Kit hidden away to the right of the override switch.

Activate the AA Guns

For the next battle to the sentry guns, take cover on the left-hand ridge, behind the generator shields. Destroy the shield generator in the distance and use this perfect vantage point to pick off the troops up ahead.

Don’t move from here until the Assault Troopers stop coming, then refill your ammo and climb up the left-hand square vent pipes to reach this upper part of the platform. A shuttle carrying two Centurions and an Assault Trooper will appear in front of you, so quickly get into cover and get a Singularity shot below them (causing them all to get caught in it when they try to land).

Head right and take cover (behind a large square piece of vent piping) from the turret gunner up ahead. If you’re sniping, look at our screenshot below showing you a guaranteed **** hit point. For non snipers, get Singularity up there to draw the gunner out and finish him off with ammo or powers.

This is the perfect sniping point to take out the turret gunner (left). Activate the controls (right) by climbing the ladders nearby.

Climb up the next set of pipes and on your left (near the centre), you’ll find a Medi-Kit you can scan for XP and gel. Run forwards, climb up the ladder on your left, climb the next ladder and then look for the switch nearby to activate the first AA gun.

Walk over to the next AA gun emplacement and look for a datapad on a pipe that you can scan for 3,750 Credits . There’s also a Medi-Kit hiding away underneath, but we’d strongly recommend leaving that alone for now (you’ll find out why in a minute). If you slide down the nearby ladder, you can pick up a Shotgun Spare Ammo Mod hiding well away from view.

See that sentry gun to your left? Run straight to it and use it straight ahead on the troops that drop out of the shuttle. Now look down and to your left for the next set of foes (easy pickings in the sentry turret). Look straight back again for the third wave, back to your lower-left for the fourth wave and finally straight ahead again for the fifth wave. The sentry gun makes very light work of the Phantoms that arrive as well.


Activate the second AA gun and immediately after the cutscene is over, begin the evacuation (unless there’s items you think you haven’t picked up yet). Kill the Assault Troopers that are dropping through the skyline and then head downstairs towards the entrance for a welcoming committee.

Make the shield generators your number one priority as it’ll be helping the Cerberus troops more than you need them to be right now. Pick off the main troops and use the plentiful cover to pick off each enemy as they make themselves apparent.

Also, be careful of the Phantom that drops down from one of the shuttles; if they get close, hit them hard with an SMG or a shotgun up close.

Soon enough an Atlas appears so immediately find cover and get to work on wearing down its armour. Overload, armour-piercing rounds, grenades etc will all do wonders to keep it at bay. Be careful of the Engineer at the top of the stairs; there will likely be a turret waiting for you in surprise. Once the Engineer is dead, the mission will be over earning you +15 Reputation points, 12,500 Credits and additional War Assets with the Ex-Cerberus scientists.


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Guide Information

  • Publisher
    Electronic Arts
  • Platforms,
    PC, PS3, Wii U, XB 360
  • Genre
    Action RPG, Third-person shooter
  • Guide Release
    14 May 2021
  • Last Updated
    15 June 2022
    Version History
  • Guide Author
    Andrew Mills, Claire Farnworth

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For years, a lone soldier has told tales of the Reapers, of their return, of these sentient machines reaching out across the vastness of space, to harvest all sentient life. But the warnings were all for nothing. Until now. The Reapers have at last come to Earth and these warnings can no longer be ignored. You are Commander Shepard, the first human spectre and elite soldier of the Alliance, tasked with uniting the galaxy in the fight to stop the Reapers destroying everything you hold dear. In your hands lies the fate of the entire Milky Way but luckily, this time, you are no longer alone.

  • All side missions completed containing the included DLC.
  • Find every single weapon mod tucked away in the game.
  • In-depth look at the major choices and consequences of each.
  • Full details on all possible Romances.
  • Class builds to get the most out of your chosen class.
  • All Biotic Combos and Tech Bursts explained.
  • Details on every Power.
  • Builds for all squad mates.
  • Trophy/Achievement guide.

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