Check out the Mass Effect 3: Retaliation Trailer (Multiplayer DLC)!
Here’s the blurb from the trailer:
The battle to save the galaxy rages on and a familiar foe returns in the largest downloadable content pack to-date for Mass Effect™ 3 multiplayer! Available to download at no additional charge*, Mass Effect 3: Retaliation ups the challenge by adding treacherous environmental hazards to existing maps and will introduce the infamous Collectors as a new enemy faction in multiplayer.
Mass Effect 3: Retaliation will be available for download on October 9 on Xbox LIVE® and the Origin™ client software and on PlayStation® Network in North America on October 9 and in Europe on October 10.