BioWare has announced that a weekend-long Mass Effect 3 multiplayer event will start tomorrow. Operation Exorcist will see players cooperating against Cerberus troops, with item rewards for squads who survive and successfully extract on Gold difficulty. Participants will also receive a Victory Pack if the community manages to kill 1,000,000 Cerberus Phantoms (you know, the sword-wielding cloaked so and sos). More details on the BioWare blog.
Operation Exorcist starts tomorrow at 12:00 midday GMT, and ends on Monday. It's only running on PC and Xbox 360, since BioWare hasn't quite thrashed out an agreement with Sony yet.