ME2 plot - derelict reaper
To pass through the Omega 4 relay safely, the Normandy will need a Reaper-designed "Identify Friend / Foe" (IFF) device. One of these Reaper IFFs may be found on a derelict Reaper hulk being investigated by Cerberus.


Upon completion of the Collector Ship mission, the Illusive Man will give Shepard the location of a derelict Reaper in order to acquire its IFF. A Cerberus team is currently investigating it. The Reaper is orbiting the brown dwarf Mnemosyne in the Thorne system in the Hawking Eta cluster. Warning: A countdown begins once you complete this mission, with consequences for crew survival if Shepard delays too long in proceeding through the Omega 4 Relay. Depending on how many of the Normandy's crew that you want to survive the game, you may want to wait commencing this mission until all recruitment and loyalty missions, except for Legion's, are completed.


Derelict Reaper cinematic intro
You will be facing hordes of Husks in this mission, with a sprinkling of Scions and Abominations. In other words, you are primarily dealing with armored opponents (if on hardcore or above; otherwise the husks have no armor) who come straight at you, and should prepare accordingly. Because of the rate that the Husks will be coming at you, some additional priorities should be considered:
  1. On higher difficulties it is paramount to have an area effect ability that can strip armor: Incineration Blast, Inferno Grenade, Area Reave.
  2. Once armor is stripped from a group of husks (or on lower difficulties where they are unarmored) they can be instantly finished with physics-based attacks. Once again area effect abilities is where it's at. So Shockwave, Throw Field, or Concussive Blast. Note that Pull Field is slightly less effective because the husks die only after the duration has expired, rather than instantly. The Adept's Singularity will usefully tie up groups of husks and make them easy targets, and will produce some insta-kills.
  3. On all difficulties it is useful to bring a character with an ammo power effective against armor, especially when evolved to be shared with the whole squad.
  4. Grunt is perhaps the most "no-brainer" squad member choice, because in addition to Squad Incendiary Ammo for armor stripping and Concussive Blast for physics-based insta-kills, his melee charge attack can kill multiple husks in one attack, regardless of armor. Finally his health regeneration and barrier abilities make him almost impossible for the husks to take down – a high level Grunt can literally run through husks for the whole mission and never go down even on Insanity.
  5. If you have Zaeed, then combining him with Grunt, and equipping both of them with the M-96 Mattock on Squad Incendiary Ammo will work wonders. The duo will simply tear the husks apart, ripping right through them (especially if Zaeed has been upgraded to Mercenary Warlord, with 50% bonus weapon damage) on Veteran or below and providing great support on Hardcore and Insanity. Heavy Inferno Grenade can quickly whittle down armor on multiple husks, while Concussive Shot or Blast can be used for crowd control, both will come in handy if you are surrounded and need help fast.
  6. If husks are frozen with Cryo Ammo and Cryo Blast, they will shatter automatically (no followup shot or ability required). This only works when their armor has been stripped, of course.
  7. On lower difficulties Sentinels can "suicide bomb" with Tech Armor, which will kill all husks in the radius. Does not work on husks with armor.
  8. If playing a shotgun-based class, especially Vanguards, you might want to consider exchanging your M-300 Claymore or M-22 Eviscerator (if you're using them) with a M-27 Scimitar. Husks without armor are weak, but come in groups, so the shotgun's relatively rapid fire will be of greater use.
  9. Finally, if you are playing on Veteran difficulty or below, this is a great place to get all 20 kills for the "Brawler" achievement – there is no shortage of husks than run right at you that can be knocked back with a melee and then finished with a weapon. Not recommended on Hardcore or Insanity, where husks are protected by armor.
  10. If you have access to it, melee damage increasing armor pieces and upgrades are useful, since fighting husks up close requires a powerful melee attack to survive on higher difficulties. Also of use are weapons with high ammo capacity, since the sheer amount of opponents can make getting to thermal clips troublesome.
  11. On lower difficulties, Jack is an extremely useful teammate during this mission. Her Shockwave and Pull powers can wipe out entire groups of husks, while her relevant class powers and upgrades will ensure she hits harder and faster with her biotic powers. If she's loyal, she'll also have access to Warp Ammo, enabling her to hit enemies with her shotgun and pistol and still do considerable damage.


Cerberus Ship

Go through the door. On the left, there is a small laboratory with a Wall Safe (+2000 credits) that can be bypassed, an accessible Terminal (+2000 credits), another Wall Safe (+4000 credits) that can be bypassed, and a Work Log. Dr. Chandana is the leader of the Cerberus research team. His log indicates the beginning of Reaper indoctrination of his team. At the end of the hallway are two medical stations with two Medi-gels, and another Work Log by a Cerberus scientist, reporting on the examination of specimens inside the Reaper. Dr. Chandana was apparently "listening" to the specimens.

Go through the airlock into the Reaper itself. The Reaper activates its kinetic barriers. Joker radios that the Normandy cannot retrieve them until the barriers come down. EDI advises destroying the mass effect core to remove the barriers. However, the mass effect core also powers the mass effect fields that prevent the Reaper from falling into the brown dwarf.

Reaper Interior

Across the catwalk the next work log plays the message:

Derelict Reaper Interior 1
Cerberus Scientist: You're married? You never mentioned that.
Cerberus Researcher: Katy had anger management issues. When my brother got married, the best man tried to hit on her. She kicked him down the church steps.
Cerberus Scientist: Wh—? Katy's my wife! I must have told you the story.
Cerberus Researcher: No. I know my wife. I remember — that day was the only time I saw her wear stockings.
Cerberus Scientist: Yeah. The kind with seams up the back. That's what I remember, too.
Cerberus Researcher: What the hell is this? How can we remember the same thing?

As soon as you pass by an explosive crate, Husks and an Abomination appear. It is best to backpedal and to blow up the crates when Husks are nearby. Husks only have melee attacks, so it is wise to keep your distance. Also, Abominations do suicide charges and will explode upon death, no matter how they died. Throughout this level in certain areas, Husks spawn by climbing up over the sides of the walkways. There will also be numerous explosive items mainly explosive crates and containers. Use them wisely, because the husks can quickly overwhelm you and your squad. Using Overload on an explosive item produces a larger blast than just shooting it. Try to use Overload on an explosive item only when there is a mass of enemies nearby to maximize the effect.

Once the Husks are down, move up to the next set of crates and be prepared for another fight. There will be more here so the nearby explosive crate is useful. Just make sure that your squadmates are not using the crates for cover. After that group is sent to oblivion, your party comments that this proves that husks must be made from Reaper technology, not geth. There's another work log in this area that plays the message:

Derelict Reaper Interior 2
Cerberus Scientist: Third day with this headache. You'd think Chandana would have let me take a few hours off. Goddamn!
Cerberus Researcher: What?
Cerberus Scientist: That thing that just… gray thing! It disappeared when I looked straight at it. Came out of the damn wall! Where we took off that panel.
Cerberus Researcher: I didn't see anything. You should lie down.
Cerberus Scientist: I'm telling you, this ship isn't dead. It knows we're inside it.
Cerberus Researcher: Calm down. Now I'm getting a headache.
Derelict reaper - altar huskathon
Head down the walkway to see and hear gunfire from an unknown party shooting Husks. Your party makes the comments about another person being on the ship. At the end of the walkway to the right are some power cells, a crate of Refined Platinum (+2000 platinum), a Cerberus Rifle that awards a Sniper Rifle Damage upgrade, and a Terminal (+3500 credits).

Turn left into an open area. Take note of the cover, explosive items, and locations of thermal clips before moving too far in. Once you move in waves of Husks and Abominations attack. A Scion is in the final wave. You can retreat back to the walkway if you need a breather or more thermal clips.

Tip: If you are very fast in bypassing and willing to forego the Heavy Skin Weave upgrade, you can go to the right after the first wave, bypass the door, leave the area, and skip the fight. However, any attack on Shepard will interrupt the bypass and you have to start the bypass over. Note that following the bypass there is a brief (several seconds) "airlock procedure" during which you will need to stay alive. Fortunately as long as you take down the first wave of husks before attempting this, the huge hordes that spawn for the last wave won't make it into this passage in time to stop you.

Once you defeat all the enemies, walk to the other end of the room. At the end of the area are a med-kit with Medi-gel, and a hackable Research Terminal which awards a Heavy Skin Weave upgrade. Some Dragon's teeth are visible, and if certain squadmates are present, the person will comment upon them. You can earn some morality points based on your dialogue choice. A Work Log in the area will play the message:

“Chandana said the ship was dead. We trusted him. He was right. But even a dead god can dream. A god — a real god — is a verb. Not some old man with magic powers. It's a force. It warps reality just by being there. It doesn't have to want to. It doesn't have to think about it. It just does. That's what Chandana didn't get. Not until it was too late. The god's mind is gone but it still dreams. He knows now. He's tuned in on our dreams. If I close my eyes I can feel him. I can feel every one of us.”

Once done here, head to the airlock and on to the next area.

Reaper Exterior

Derelict reaper - alien geometries
Bypass the door and go through the airlock. A cutscene starts. A geth sniper with bits of N7 armor attached to it snipes several Husks by Shepard's party. The geth recognizes you as "Shepard-Commander", then leaves.

More Husks and an Abomination soon appear; deal with them and then put your squad into cover and walk down the stairs. Once you go past the crate in the center, there will be Husks, an Abomination, and a Scion. You can retreat back upwards to make the stairs as a chokepoint.

Since Husks are melee enemies, it is generally best to stay "on the move" rather than getting in cover - this makes it much less likely you will be trapped by husks, and by moving around you will often confuse them. Obviously as the Scion approaches you will need to either interpose objects between you and it, or move perpendicular to the line of its shockwave. The site of the first battle after you leave the airlock makes a good battlefield-of-last-resort to pull back to - you have room to run around to dodge husks but also the giant tank on the right side to interpose between you and the Scion.

Once the enemies are dealt with, go up the stairs at the other end. To the left will be med-kit with Medi-gel and a Terminal (+3000 credits). Advance carefully because moving too far will result in attacks by more Husks and one Abomination. Once they are down, nearby there is another Terminal (+3500 credits). Down the stairs are more Husks, Abominations, and a Scion. Use the stairs as a choke point again and then take them out. Once done, a med-kit with Medi-gel is on the staircase. A Cerberus Shotgun with a Shotgun Damage upgrade and some power cells await you at the bottom of the stairs around the corner. Further on, up the ramp, are a bunch of thermal clips and another Terminal (+3500 credits). This area will be crucial in the next fight.

The next battle will be Husks, Abominations, and two Scions. This battle will be tough no matter the difficulty because of the amount of enemies that come at you. The Husks will charge at you. Keep your squadmates, and yourself for that matter, back or you will regret it. Use powers, specialized ammunition, and shotguns for close up damage when you need to.

Reaper IFF
One way to finish this area easily is to retreat back to the room you just came from, where only three or so husks and the two Scions will approach, since the additional husks only spawn when you get close again. Once the Husks are down, focus on the Scions. The Scions will approach last and are easier to deal with than the Husks; the best thing is to take one yourself and use your squadmates against the other. Once they are down, move on but be careful.

When you reach a left turn, get ready because Husks, Abominations, and two more Scions will come crawling over the railings and from the core. Take them out and do not be afraid to backpedal if necessary.

After they all have fallen, pick up the power cells and a little further down near the doorway is a med-kit with Medi-gel. Bypass the door and enter yet another airlock. Inside is the Reaper IFF and a Wall Safe (+2500 credits) that can be bypassed.

Tip: Save your game at this point before the final battle. If you are going to use the M-920 Cain to one shot the Core then get the weapon ready before you go into the room. This saves you a few seconds of waiting for the weapon to ready.

Mass Effect Core

Derelict reaper - legion in the core
Once you enter, the game auto-saves and a cutscene plays. The geth sniper from before is manipulating some controls. It drops a barrier allowing Shepard and the team inside. However, Husks overcome the geth and knock it out.

The objective of the battle is to destroy the Reaper Core, but an iris often closes to cover it, preventing any damage. The iris is open at the beginning, but closes when attacked or when the initial Husks are dead. It will stay closed for between 45 seconds and a minute. Subsequent closures are between 30 and 45 seconds in length. Meanwhile, waves of Husks and Abominations attack you. They respawn as long as the Core is closed, but they always come from the same areas every time. Use that to your advantage if you start to get overwhelmed.

You can only damage the Core when it is open. It will stay open until you have taken its health down by a third, so do not feel pressured into immediately firing into it when it opens up - just take pot shots whenever you're presently safe from husks.

When the Core is open, enemies do not spawn, so it is possible to eliminate them all, then sweep up thermal clips and let powers recharge before shooting up the Core, though this may of course result in the spawning of more total enemies. Squadmates will also revive when the Core is open and all enemies are dead, so it may be best to put off using Medi-gel if the Core is going to open soon. The thermal clips around the room will regenerate so there is no lack of ammunition as long as you can get to them.

Derelict reaper - core husks
Unlike the rest of the level, there are no handy explosive items. On the lefthand side on a table, there's a Laptop (+1000 credits). It must be taken during battle since there will be no opportunity to walk around the area afterwards.

Every enemy here is effectively a melee opponent, so mobility is key. If you can just avoid being trapped/surrounded by husks you can keep on the move and be fine. Your best position, when possible, is the top of the central bridge from which you have a commanding view of both sides of the room and can throw area effect powers at the masses of husks. But if things get too hot on the bridge then flee down to one side or the other where there is more space to dodge around - remember the husks aren't very good at stopping and turning around, and use their lack of maneuverability against them.

The Core is not a "targetable" object, so be wary if you are using the Missile Launcher to damage it. It will tend to lock onto other enemies instead of going after the Core, unless you are at the apex of the center walkway.

The M-920 Cain can destroy the Core in one shot on any difficulty. The easiest method to getting through this area is to not move when the battle begins (as the Core will remain open while you're far away and the Husks are still alive), switch to the M-920 Cain, and shoot the Core.


Derelict Reaper escape
Once the battle is over, a cutscene plays. The party debate what to do with the fallen geth, but Shepard makes the decision to take it with them. Joker brings the Normandy alongside the falling Reaper. The squad retreats while pursued by hordes of Husks. They take advantage of the microgravity by tossing the geth into the Normandy's airlock and jumping in afterwards.

In the debriefing, Miranda states that the geth is being stored in EDI's AI Core. Jacob and Miranda debate what to do with the recovered geth. Jacob is in favor of tossing it out the airlock. Miranda wishes to give it to Cerberus. If you decide to the talk to the geth, it will stay onboard deactivated, waiting for you to talk to it, and you gain 20 Paragon points. You can also hand the geth over to Cerberus for 50,000 credits and 20 Renegade points, but Legion is permanently lost as a potential party member.

E-Mail Messages

For completing this mission, and deciding to keep Legion, Commander Shepard receives this message from the Illusive Man.

From: Illusive Man


I'm pleased that you were able to recover the Reaper IFF, and I've sent EDI all the necessary protocols to get it integrated successfully into the Normandy's systems. With luck, this will give us the ability to get through the Omega-4 relay and take the fight to the Collectors on our own terms.

I've been notified about the intact geth and your decision to keep it. If you believe that it can be trusted, then go ahead and activate it. Just make sure that EDI is adequately protected against any hacking attempts.

It's not necessarily the decision I would have made, Shepard, but this is your call. You've already cast a wide net in your recruiting efforts, and if the geth are willing to fight the Collectors, then we can use them on the team. I trust you to get the job done, whatever it takes.

Alternatively, Shepard receives the following e-mail, in case Legion is handed down to Cerberus:

From: Illusive Man


I'm pleased that you were able to recover the Reaper IFF, and I've sent EDI all the necessary protocols to get it integrated successfully into the Normandy's systems. With luck, this will give us the ability to get through the Omega-4 relay and take the fight to the Collectors on our own terms.

I'm extremely pleased with the intact geth you retrieved. It's a fantastic study opportunity and will definitely help our efforts to develop technology to fight the Reapers. Accordingly, I've transferred a bounty to your account.

Mass Effect 3 Consequences

If Legion was sold to Cerberus, it will appear as an enemy during Priority: Cerberus Headquarters, and a Geth VI will take its place during the three missions it appears in. If it wasn't activated at all, the same will happen. If it was activated, assuming it survived the suicide mission, it appears in the aforementioned missions and it will be possible to gain both geth and quarian allegiance.


Mission Summary

Reaper IFF successfully retrieved.

Loss of Cerberus team on the Reaper vessel unfortunate but unsurprising. Will use team's health records for comparisons against husks encountered on Reaper for possible insight into indoctrination and husk conversion process.


  • It is possible to see Legion standing at the far end of the room when you turn left after the two husks are dropped by its sniper fire. If you look around in the back of the room the shots came from and zoom your weapon, Legion can be seen standing on the ledge at the back. It will walk away once you enter the room.
  • The work log near the Heavy Skin Weave upgrade is most likely a reference to H. P. Lovecraft's The Call of Cthulhu. More specifically, it references the couplet "In his house at R'lyeh Dead Cthulhu waits dreaming."
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