Players can experience the entire story of Commander Shepard, including all DLC missions, in main story missions of Mass Effect 3. The missions in the Omega DLC allow Shepard to return to this hub and experience its dark underbelly. Mass Effect 3: Omega is one of the more difficult DLCs to start, as Shepard will need to do Aria a few favors before it unlocks.
Following Priority: Palaven in the main story of Mass Effect 3, Shepard will find Aria at Purgatory, the night club on the Citadel, in a pseudo-VIP section. They can talk to her to learn more about what happened to Omega, what Aria intends to do about it, and how she can help the War effort. Once Shepard completes her smaller side missions, Aria will reach out to them via email. At this point, players will be able to start the DLC whenever it fits in their story. Once they start the mission, they will need to see it all the way through before they can return to the main campaign. Here's how to start the Mass Effect 3: Omega DLC in Mass Effect Legendary Edition.
How to Unlock the Omega DLC in Mass Effect Legendary Edition
To start the Mass Effect 3: Omega DLC, Shepard will need to find and speak to Aria at Purgatory. This option becomes available any time after Priority: Palaven. When Shepard asks her about the impending war, she will suggest getting the three major mercenary organizations from across the galaxy, the Blood Pack, Eclipse, and Blue Suns, to call a temporary truce and work together under Aria.
Shepard will need to visit several locations around the Citadel to meet with each mercenary group's leaders. Some are more interested in helping Shepard than others. Shepard will need to complete a few side assignments, localized to the Citadel, to convince some of the leaders to agree with the proposition.
Once Shepard completes this questline, they should return to Aria at Purgatory to let her know. Some time later, Shepard should receive a message from Aria at their Private Terminal on the Normandy, asking them to her on Dock 42 to talk about her plans for taking back Omega.
Getting to Dock 42 is similar to getting to Anderson's Apartment for the Citadel DLC or Dr. Bryson's lab for the Leviathan DLC. The Normandy will need to fly to the Citadel, and players will need to choose Dock 42 from the list of options. A cutscene will play, in which Aria lays out her infiltration plans and tells Shepard to her private Fleet, alone, when they are ready. This conversation unlocks the coordinates for a new area near the Citadel on the Galaxy Map, Aria's Fleet.
To start the Omega DLC missions, Shepard must use the Galaxy Map, travel to Aria's Fleet, and dock. They will be prompted to select a loadout, though they will have a chance to change this later at Priority: Rannoch, or between Priority: Rannoch and Priority: The Citadel III.
Mass Effect: Legendary Edition is available for PC, PlayStation 4, PlayStation 5, Xbox One, and Xbox Series X/S.