Mass Effect 3 will be receiving another free update to the four-player co-op multiplayer side of the game on October 10, 2012. BioWare was happy to announce the news today on the official website which details the return of the reasonably unhappy Collectors, who were the main protagonists in Mass Effect 2.

The new DLC, Retaliation, will not only bring in back the Collector bad guys, such as Scion, Abominations and the Praetorian,  but also new Drones from the Geth and the Dragoon from Cerberus. A few new playable characters will also be added including the Turian Havoc Solider and Ghost Infiltrator. Maps will be updated with new hazards as well such as Sandstorms, Swarms, Acid, and more.

Of course, with every update we get new weapons, these being some of the Collector-types that we haven’t seen since the second game, but the biggest change will be the new Challenges à la achievements mode.

Challenges will track your gameplay, such as weapon usage, and unlock bonuses through the completion of mini-goals. Earned Challenge Points can then be used for vanity items such as different character banners for the lobby. You can read about the complete details on the official website here and take a look at the new trailer below.