This is a relatively short mission, so begin by running to your left and collecting the Rosenkov Materials Chestplate from the top of some metallic crates. Now, before heading to the sergeant, look to the left walkway where you can find a Medical Treatment Plan resting on some crates. These plans will allow you to complete the side mission Citadel: Chemical Treatment .
Speak to the sergeant and the crates ahead of you will soon be lifted; when they are, go forwards then look right for a set of controls on a terminal. Use the middle button to lift a crate and the left and right buttons to move the arm in the relevant direction. Once both crates have been moved to the right, the blockage has been relocated, allowing you to proceed into a well-ventilated area of the reactor. Also, look near the left corner of this room for some salvage you can scan for 4,000 Credits .
Ventilate the Area
Head back out and run around the walkway to your right and you should come across an ammo dump near a terminal you can use to clear the fuel rods of radiation gas. Turn around, head down the ramp and activate the first rod.
When you do this be ready for an encounter with a Marauder and Husks, but your main priority should be the Reaper shield generators located near the bottom of the ramp to your left and up behind you near the ceiling.
Two reactor tanks will now need sealing. The first one can be sealed fine; after sealing the second one around the corner, you’ll trigger off a bigger Reaper battle with around six Marauders and multiple Husks.
Set your team up so they’re covering the top of the nearby ramp and destroy the three Reaper shield generators. The first one is halfway down the ramp, the second is up above the same ramp on the right and the third is to the left of the ramp.
With the shield generators taken care of, focus your attention on the Marauders and leave your squad to fend off the Husks. Stick behind cover near the left side of the ramp and look down around this area for the Marauders showing up; this should give you plenty of time to either headshot them or whittle their health away before they get close.
If the Marauders stop appearing, turn around in case they’ve appeared behind you; take advantage of them going after your AI teammates and get up close with an SMG or shotgun for massive damage.
When you’re asked to provide help, not doing so will earn you Renegade points whereas offering one of your team will earn you Paragon points. Whoever you give shouldn’t be good against Brutes, because as soon as you send that person away, you’ll be up against a shielded Brute and two shielded Marauders. We kept James with us and used his grenades (and our sniper rifle) to drop the Brute in a few seconds.
Hit the initiate start-up button before leaving. Also nearby, there’s a PDA you can scan near the reactor panel for 3,000 Credits . Head back to the start of the map to finish the mission and be rewarded with +5 Reputation and 10,000 Credits .