After the grueling battle with the (potentially multiple) Atlas mechs in the hangar, feel free to head out to the next area of the level. Along the way, search for the M-37 Falcon Assault Rifle in the flaming wreckage of the wall. Examine the door to the left, and ask EDI to hack through it. She will spy on the Cerberus communications as she opens the door for you. She will warn you that Cerberus is now fully aware of your intrusion (the airplane through the wall couldn’t have helped that much) and are organizing now to cut your invasion short.

Proceed through the door to find evidence of this fact. You will enter a dark, mechanical area swarming with Combat Engineers, turrets, Assault Troopers, and Centurions. Take cover behind one of the metal walls, using the piping and pillars for cover. Stalk around the room to get a better vantage point on your enemies. Leave your squad near the beginning of the area to draw the enemies’ attention if you’re playing as an Infiltrator, Sentinel, or Vanguard, as you can distract them with your squad-mates and flank around for a close up attack from the side. Use Tactical Cloak, Tech Armor, or Biotic Charge to get in close and deal some heavy damage with a Shotgun or Assault Rifle. Alternately, you can hang back and group your squad around you, making your position better defensible. Use an Assault Rifle, Sniper Rifle, or SMG to fend off the enemies and your squad’s Biotics and Tech to create Singularities and Decoys.

At the far side of the room, you will find a Nemesis sniper. The red laser of the Nemesis’ rifle may be a bit hard to distinguish against the red haze of the background, so be careful not to get caught in it. As you head down towards the end of the room, be on the lookout for the sniper. Charge up to her and kill her in close range, where she is relatively defenseless. From this area, if the rest of the area is still full of enemies, you can look down the length of the arena and pick off whichever foes still remain with your Sniper Rifle.

When all of the enemies in the room are dead, head for the ladder to the side of the back of the room. Be sure to grab the Med Kits and the Salvage from the terminal right after the ladder. When you reach the top, Allow EDI to open the next door, which will be locked. As EDI is hacking the computer, check the computer itself to find three logs detailing Project Lazarus, then open up the door. There will be a large hole in the middle of the floor ahead of you. You will have to jump down the hole in the floor to reach the lower floor again, since there is no other way around. Look for the Serrice Council Greaves near the hole. You will find yourself in a similar room to the last one that you cleared, full of Combat Engineers and their turrets, along with normal Assault Troopers. There will also be numerous energy barriers that you can take cover behind. Watch out for the Assault Troopers, who will cover their allies by immediately firing upon you so that the Combat Engineers can set up their turrets. Order your squad to go ahead and attack the Assault Troopers so you can focus on the more annoying Combat Engineers. Once they are dead, you can safely focus on the turrets that they laid down. Use armor-weakening powers such as Warp or explosives like Grenade to take out the turret quickly, so that its rapid fire can’t take down your shields.

This can be easier said than done, depending on which class you are playing as. Vanguards will have a pretty easy time dashing from one Combat Engineer to the next using Biotic Charge, before detonating a Nova blast in the middle of the Assault Troopers. From there, mopping up the remaining opposition will be a simple matter of whipping out your Shotgun and going to town. Infiltrators can use Tactical Cloak to get in some pretty big hits against the Combat Engineers and their turrets. Other classes, however, will definitely want to stick close to their cover as the turrets chip away your cover and the footsoldiers attempt to flank you. Sentinels may be able to use Tech Armor to lessen the blows, and Soldiers can use Adrenaline to deal more damage, but these powers alone won’t be enough to best the turrets in a head-on battle.

After this battle, head towards the ladder and take cover. Two Centurions will climb down the ladder. Shoot them as they descend to kill them before they can become a threat. Climb up the ladder when they are dead and examine the door. Again, EDI will need to hack through it. While she does this, examine the console to the side to watch videos about EDI. If you did not take on the Grissom Academy mission earlier, you can also pick up a PDA here which will tell you that Jack was unfortunately disposed of by Cerberus troops during the mission. Head through the door. Search the desk to find a PDA, and look for Med Kits on the wall to the left. As you exit the door, turn right to find another door containing more Med Kits and the Demulcore Overlay item. You can also find another console with more videos here. This one, however, contains video of the Illusive Man himself, along with Kai Leng. He will be eagerly anticipating a battle against you.

Head back out to the main hallway. Here, you will find a blue drop that leads down to the lower level. Drop down the hole to reach the next area. Most hauntingly, however, is the Reaper hanging in this room. The Reaper is being used to power the entire base. Speak with your squad-mates about the Reaper hanging in the facility, then head out to the walkways beyond the disturbing laboratory.