Mass Effect 3's Omega DLC will be the most expansive and expensive add-on yet, maker BioWare has announced.

The single-player campaign expansion launches for PC, PlayStation 3 and Xbox 360 on 27th November for 1200 Microsoft Points or $15 (about £10). European PlayStation players will likely see it on the 28th.

Omega will be "double the size" of the largest Mass Effect 3 DLC so far, Mass Effect 3 producer Mike Gamble explained at New York Comic-Con. (In terms of actual game content Gamble is likely referring to this summer's Leviathan DLC. In terms of file size the largest is the 2GB Extended Cut, although that is the Xbox 360 DLC file limit).

Omega will also be the most expensive Mass Effect 3 DLC so far (or of the entire series, if you don't count Mass Effect 2's 1200 Point Cerberus Network pass which came free with new copies).

The expansion will see players team up with ousted Omega ruler Aria T'loak to retake the station from Cerberus control.

Omega's story follows the Mass Effect 3: Invasion prequel comics, which saw evil General Petrovsky move in and secure the space station for the Illusive Man's evil clutches. Petrovsky will return in Omega, Gamble confirmed. We'll also get our first glimpse at a female turian.

"New enemies" will also be included - likely the Cerberus Dragoon class added this week to the game's multiplayer in the bumper Retaliation add-on.

The existence of an Omega-based storyline has been known about since before Mass Effect 3 launched. The missions were originally included in early versions of the game's script, before being excised (and presumably expanded) for use in a separate DLC pack. An image of Aria T'loak's squadmate icon was actually broadcast during an official BioWare Pulse video.