Update: A new trailer confirms a lot of the details below, including how players can transform into Michael Myers on the new Fog map - other players will want to get a-running when that happens. It also details the first chapter, Nightfall, of the four-part Extinction campaign. As for the launch date, it's confirmed that it only applies to the Xbox One and Xbox 360.
It's official: Call of Duty Ghosts gets its first DLC, Onslaught, on January 28, True to series form, the due date first cropped up on a GameStop display, but Infinity Ward provided official confirmation last night. There's no confirmation the date only applies to the game's Xbox versions, as the display noted, but that would be in line with Activision's timed exclusivity announcement at E3.
As for what's in the DLC, that big spidery thing is coming to Extinction, for one. There's also an air of Extinction to Infinity Ward's newly teased video, with what sounds very much like the Halloween music in the background - maybe something to do with the Mike Myers custom game?
We know there's a four-part Extinction campaign spread across the four announced DLC packs, and the GameStop display noted - surprise surprise - the first part is in Onslaught. If the display is accurate, you can also expect four maps called Fog, Bayview, Containment, and Ingition, as well as a Maverick AR & Sniper rifle thrown in for good measure.
As for the price, there's no new intel on that for the time being.