This mission is automatically available after completing the prior plot mission.
Note: After completing this mission, Priority: The Citadel II begins immediately upon your next return to the Citadel, causing some side missions unable to be completed. As such, be sure to do the following side missions and interactions before attempting this mission:
- Benning: Evidence
- Citadel: Alien Medi-Gel Formula
- Citadel: Barla Von
- Citadel: Biotic Amp Interfaces
- Citadel: Hanar Diplomat
- Citadel: Improved Power Grid
- Ismar Frontier: Prototype Components
- Any interactions with Kelly Chambers (only available if she survived the Collector Base assault in Mass Effect 2). Also, if you visit and tell her to change her identity, she will remain available after the end of Priority: The Citadel II.
- Conversing with Matriarch Aethyta in the Apollo's Cafe.
To complete the treaty between the krogan and the turians, the Clan Urdnot leader (Wrex / Wreav) insists that the genophage must be cured. To do this, the genophage cure must be dispersed at the top of the Shroud, a tower installed by the salarians to stabilize the atmosphere of Tuchanka and covertly used to disperse the initial genophage virus. A salarian STG member will ensure that this takes place. That member will be Mordin Solus if he is alive, Padok Wiks if he is not.
Travel to the Krogan DMZ and the planet Tuchanka and land at the Shroud site. You will discover that the Reapers are using a Reaper Destroyer on the Shroud in order to poison Tuchanka's atmosphere. To destroy it, the krogan plan to attack from the ground while turian fighters deploy for air support. You will also be informed by the Salarian Dalatrass that the Shroud has been sabotaged to prevent dispersing a cure, and that you could choose to trick the Krogan into thinking that you dispersed the cure but keep it from working in return for getting support from the Salarians.
You will then take a shuttle down to the surface. The Urdnot leader sent word for the krogan clans to assemble at the Hollows, a sacred krogan meeting ground. During the conversation, you can reveal the Dalatrass' offer to sabotage the cure or just remain silent. If you choose to reveal, you will be interrupted by a message that the Hollows are under Reaper attack. When you reach the Hollows, you need to fight off waves of Husks swarming the area. You will gain 300 experience points after successfully holding off the Husks. In the ensuing scenes, if Wrex is alive, tensions mount between him and Wreav, who is one of his most disloyal supporters; if Wreav leads, Jorgal Thurak takes his place. Eve intervenes during the rising conflict and makes a rallying call for the krogan to unite against the Reapers.
The krogans head out in a convoy towards the Shroud. While travelling, you given the option again to reveal Dalatrass' deal or keep quiet about it. Soon after, the convoy came to an immediate halt and the team gets down. You can pick up a Shotgun Smart Choke upgrade, a Pistol Magazine Upgrade, a Pistol Melee Stunner, a Death Mask helmet armor, Graal Spike Thrower shotgun and 2 Med-kits. Speak to the Krogan Scout who tells you that the road is damaged and the convoy can't proceed further.
However, the turian air support has already begun their attack. A fighter is shot down and hits a truck. Shepard radios the Urdnot leader to get out while you have to find an alternate path to the Shroud. At this point, you gain another 150 experience.
The only path left is through the ruins. Jump over a gap and head into the tunnel.
Escape the Catacombs
You're now in an ancient krogan city which has been in disuse for millennia. Go down the stairs into the first room, and either jump through the gap off the ledge on your left, or go down the next set of stairs to your right. In the second room, there is a door to your right and to your left. Go through the door on the left, and on the right hand wall of that room is an Ancient Krogan Artifact, which is a painting on a wall, worth 8,500 credits. Return to the door on the right, go down the stairs. Right before another jump down, Shepard and the team experience strong tremors. The Urdnot leader radios that they're not experiencing similar on the surface, while Eve suggests that it could be something else, warning that Kalros, the mother of all thresher maws, is said to live in the region.
Jump down the ledge at the end of the path and turn to the left. In the far end of this area, you can salvage another Ancient Krogan Artifact on the wall for 8,250 credits. After retrieving it, go to the other side of the room and turn left into a tunnel where you'll find the final Ancient Krogan Artifact, a painting, worth 8,250 credits on the right. Further along the path, you can examine a dead Ravager and then head up the stairs into the light. You will gain another 300 experience after exiting the catacombs.
As you move forward, you will fight a wave of Cannibals and Ravagers. Then when you move forward again, a second set will drop from the sky. Once they are finished off, move forward and turn right to jump over the gap. A set of Cannibals will appear followed by some more coming around the corner, and finally one of the Brutes will come around the corner. The second wave is triggered by leaping over a gap. None of the enemies can follow you if you retreat back over the gap after triggering the wave, allowing you to kill them without risking direct combat.
After the second wave, go forward, around the U-turn, and up the ledges on the left. At the same time, the krogans will be talking about a plan to stop the Reaper, but Eve will say that the commander has enough to worry about. Once you are up the stairs, a third wave of Cannibals, Husks, and Ravagers will attack. Once they are dead, head for the right side of the open area toward the krogan statues.
Upon reaching the second bridge, Kalros appears and chases the convoy, damaging the bridge in the process. Jump over the gap and go to a memorial area further up. As you approach the small bridge, a wave of Cannibals and Husks will attack. After some more dialogue with the convoy, more Husks will attack along with some Marauders. Once they are dead, you will find a SMG Scope upgrade on the left side of this area. Head down and back up the two short set of stairs where the Marauders came from and find an Assault Rifle Extended Barrel upgrade on the left.
Turn right and drop down off the edge of a series of ledges toward the dunes to trigger a cutscene. Shepard and his team board the convoy, but the second truck carrying Wreav/Thurak is pulled into the ground by Kalros.
The Maw Hammers
Eve suggests using the ancient Maw Hammers to summon Kalros to the area and distract the Reaper away from the Shroud. Shepard agrees and head out to activate the maw hammers, while Mordin or Padok Wiks heads out in another direction to finalize a cure to the Genophage.
Clear off the two sets of Cannibals and go up a flight of stairs on the left. At the top of the stairs, pick up a M-5 Phalanx Heavy pistol. When you attempt to cross the bridge nearby, the Reaper blasts the bridge and Shepard falls down below. From here, the Reaper starts blasting at you. So stay in cover and move up between his blasts. Once you reach the cover spot in the middle, the turian fighters appear to draw the Reaper's fire.
To reach the Maw Hammer controls, Shepard must fight through a gauntlet of Brutes, while avoiding getting crushed by the Reaper. The Brutes spawn continuously until both Maw Hammers have been activated. It's possible to simply dash through the battlefield, activating the Maw Hammers using Shepard's superior speed.
The Reaper's legs are the biggest threat: one hit will drop your shields at the very least; if the Reaper lands a second hit before your shields regenerate, it's an instant kill. Thankfully, many of the leg stabs are focused on the two catwalks leading to the maw hammers. As such, the safest approach is to run across the arena and then walk down the catwalks. Also, you can see where the Reaper is going to hit roughly two seconds before it happens, by looking for the giant shadow cast by its leg. That's enough time to dash to the side and avoid being crushed.
When both hammers have been activated, they successfully attract Kalros. In stunning fashion, Kalros bests the Reaper, dragging it beneath the surface of Tuchanka's wasteland.
With all opposition from the Reapers destroyed, Shepard and the convoy approach the Shroud. However, the Shroud sustained damage in the fight against the Reaper - it is falling to pieces as Shepard approaches. Within, Eve's STG caretaker--Mordin Solus or Padok Wiks--is attempting to stabilize the structure. He will also report on Eve's status: in the absence of Maelon's data, she will have died whilst Shepard handled the Reaper.
All outcomes are available regardless of whether Mordin or Wiks is present, so for convenience we will refer to the character as "Mordin."
At this point, Shepard may either let Mordin go or stop him to sabotage the cure per the Dalatrass's request. There are multiple outcomes to this conversation:
- If Shepard did not reveal the sabotage while in the convoy to the Shroud, Mordin will realize something is wrong. Either Shepard tells Mordin about the Dalatrass's deal or Mordin will correctly surmise it. Unless stopped by persuade options in conversation or by force, Mordin will ascend the tower to repair the STG sabotage, successfully releasing the genophage cure, but dying in the process.
- If Shepard warned of the Dalatrass's deal in the convoy, Mordin carries through the counter-sabotage and deploys the cure, sacrificing his life in the process. You may use a Paragon interrupt just before Mordin steps into the elevator to get some morality points, but it won't change Mordin's fate.
- If Shepard tries to make Mordin abandon the mission while Wrex and/or Eve are alive, Mordin will refuse to listen. Shepard is offered a Renegade interrupt to gun him down. If Shepard does not take it Mordin will cure the Genophage.
- If Shepard has not reavealed the sabotage and tries to make Mordin abandon the mission while Wrex and Eve are both dead, Persuade options can be used on Mordin to convince him that it is for the best if the Shroud remain sabotaged and the krogans fooled into believing the genophage cured. Both Mordin and Wiks agree to fake their own deaths, but Mordin becomes a War Asset at the Crucible project, whereas Wiks, according to an e-mail he sends you after the mission, instead seeks out a quiet colony world where he will work as a farmer and take his secret to the grave.
This mission results in the following outcomes:
- The turians provide the 43rd Marine Division, Seventh Fleet, and Engineering Corps. Primarch Victus can no longer be found on the Normandy.
- Whether or not you actually cured the genophage, the krogan provide the the Urdnot Leader, Krogan Clans, and Clan Urdnot. You will also earn Krogan Mercenaries if Wrex is leader. However, they may be diminished in strength if Eve died or Wreav is leader. Furthermore, if you did not cure the genophage, Wrex will eventually find out, and confront you during Priority: The Citadel III, leading to his death and a diminishing of the krogan's military strength. If Wreav is the Urdnot leader, he never discovers the deception.
- If you cured the genophage, you will receive no salarian assets at this time, leaving the STG force you gained from Sur'Kesh as their race's only representatives at this time. Sabotaging the cure grants you their First Fleet and Mordin Solus (if he was spared).
Given that the Salarian First Fleet's military strength is 150 points while the total combined military strength of Clan Urdnot and Wrex is 330 points, with another 75 from Krogan Mercenaries, a Renegade-minded player should be aware that not curing the genophage with Wrex as leader will actually weaken your force, where as Wreav as leader will provide a total of 475 between the two races.