Note: To unlock this mission you must have first completed up to and including Priority: Palaven and united the three mercenary factions under Aria’s rule as well as purchased the Omega DLC pack from your respective store of choice.
Open your private terminal and find the mail entitled "Omega: It’s Time." Your next port of call is Dock 42 to meet with Aria’s associate Bray. After the cutscene, you will be back on the Normandy. Travel to where Aria’s fleet is docked near the Citadel to begin the DLC.
Warning: After activating this mission, you will be on Omega for some time so complete anything you need to do beforehand and make sure to retrain any powers and select the bonus power you want to use. Energy Drain or Dominate are good choices.
Omega: Aria T Loak
Shepard and Aria will crash land in a room full of Cerberus Assault Troopers and Centurions. Take this opportunity to spec Aria’s powers. Aria’s shield-piercing Lash evolution is particularly useful versus many of the troopers making them vulnerable to biotic explosions.
Her Flare ability has a long recharge but can self-detonate and acts kind of like a biotic grenade so is excellent at decimating large groups of enemies. Use it when enemies clump together but use it sparingly. Make sure to get her Biotic Boss squad health/shields as the final evolution.
Once you’ve finished, set upon the Cerberus troops. If you took Energy Drain as your bonus power, you can put it to good use against the Centurions, making them little more than an annoyance. Energy Drain can also be used to stun Assault Troopers if they get too close.
Tip: As an Infiltrator you can cloak, fire a power and then still have time to line up a headshot before uncloaking. This makes killing harder shielded enemies a piece of cake and can restore your shields if you use Energy Drain. It also makes the cooldown on Tactical Cloak a lot faster.
There are two Med Kits in here if you need them. Open the blast doors when you’re ready but immediately take cover as Cerberus will arrive for another attack. There’s only a couple of Guardians and Centurions to worry about however.
Open the door at the far end to activate the elevator. There’s nothing of interest in the next room so move on. Take cover as soon as you open the door as more Cerberus soldiers wait in the next room.
Focus on the Combat Engineers as their deadly Turrets will rip you into shreds should they see you. If you’re quick enough, you can let off a Flare as the Troopers drop in from the ceiling and damage or even kill several of them before they get a chance to attack.
A Med Station is at the door near Aria but there is nothing else to collect so follow Aria. Take cover next to where she is initialising the system as Cerberus will try to stop you. They will arrive from the right with a Nemesis in tow.
Be aware of when to break cover to avoid the Nemesis taking pot shots at your scalp. Swiftly deal with the rest as they shouldn’t pose too much of a problem. Once repressurisation has finished exit through the back door.
Bypass the door where you will be assaulted by more Cerberus soldiers. Focus on the Engineers again. Both are grouped together so you can use Flare to strip them of their shields, softening them up for target practice or more explosions.
Beware of the Guardian and Trooper who may try to flank you. After the fight, use the Defense System Controls. There is a Renegade interrupt where you can shoot the surveillance camera. Now, move on to the far exit and into the elevator.
When you arrive at your destination, quickly grab the 3000 Credits from the safe and then prepare to attack more cannon fodder. They will try to flank you so be ready to use Flare/grenades and move if you have to.
Open the garage door and ahead of you, you will find a Pistol Heavy Barrel I . Pick up the tools for 1500 Credits . Go to the left and jump over the crates to go to the next area where more enemies lie in wait. Kill them, grab the Med Kit and move on.
Board the elevator and when you get off, pick up the scrap metal for 2250 Credits. Drop off the ledge and be ready: you’re about to find out what those forcefields are for.
Rampart Mech First Battle
This is where Energy Drain can save your life as the mechs are incredibly fast, have a lot of armour and hit hard. They also remain electrified upon death so don’t walk over their bodies. Use Energy Drain to stun them and line up a nice headshot to take them out rapidly.
If they get too close, use Flare to stun them allowing you to move to different cover. Disruptor rounds work well too and any other tech powers. Keep creating tech bursts or biotic explosions and they will soon die. Always aim for their heads if you can.
Go towards Aria to proceed. She will open up an escape route so leave through there. There’s some more goodies in this room, notably a Shotgun High-Velocity Barrel I which is particularly handy for Aria or shotgun-wielding Shepards.
Go down the ladder for another cutscene. Turian females do exist! Nyreen is a powerful biotic and works well in conjunction with Aria or a biotic Shepard. Spec her now. If using a tech Shepard, spec more into Overload and Incinerate. Make sure to fully upgrade her Lift grenades as these are exceptionally useful for later battles.
Her biotic field is good for increasing damage protection or power damage but you don’t really need it. After you’re done, pick up the scrap metal for 3000 Credits and the N7 Valkyrie. This is a more powerful Vindicator but must be upgraded to make an impact on Insanity.
Use this opportunity to equip Aria and Nyreen with stronger weapons. You can find a weapon bench through the next door so equip high-velocity mods and extra damage if you have them. Run forward and up the ladder. In the next area it is possible to shoot the mechs from here but it takes longer so go around the side into the room proper.
Cerberus Cannon Activation Fight
Take cover quickly as mechs will be there to greet you. Let rip with a combination of Energy Drain, Overload and Flare/Lift grenades. They will soon notice that you are flanking them and retaliate so be ready to move as they will rapidly turn the tide on you.
If you move up the stairs to the left, you can stop the Atlas targeting you and funnel the enemies through there. You may need to move quickly so don’t stay in cover too much and just strafe the area. You can set your squad to stay at the bottom to distract the enemies.
Once the mechs are dealt with, Bray will mention an Engineer hacking the cannons so find him. They arrive from balconies to the far left and right so if you’re a Sniper, take cover at the back and pop their heads. Otherwise, close in a little and use tech powers and mid-range weapons.
This part is not hard as the Engineer is clearly marked. A few well-placed shots will kill him fast. When he’s down, Bray mentions that the cannons must be armed manually. It just so happens that an Atlas is near the cannon controls so rectify that problem first. Ignore the troops because as soon as you arm the cannons, Bray will sort out the rest.
Time for a bit of a respite so make the most of it. There are two sidequests available here. The first is to assist the mechanic by finding some Kehri Inverters somewhere on Omega. Don’t worry about this for now as these will be pointed out in the guide when applicable.
The other is to assist the hacker by finding terminals. Again, these are found in the next stage so forget about them for now. There is an armour locker and weapon bench at the back if you need to change equipment. When you’re done, speak to Aria to initiate the next mission.