The War Games Map Pass will include access to three future map packs for a total of nine new competitive multiplayer maps. The pack offers the future DLC bundled for 2000 MS points (£17 / $25), a 15% discount over buying them individually.
The pass will also give players three exclusive in-game items, the Spartan-IV "Scanner" and "Strider" helmets and the "Falcon" in-game emblem.
Also revealed today are class specialisations for online multiplayer, allowing players to continue progressing past level 50 on unique paths. There will be eight specialisations in total, each unlocking new armour mods, emblems, visor colours and weapon skins unique to that specialisation.
Two specialisations, Wetwork and Pioneer, will be available to all users when Halo 4 releases. The Wetwork specialisation provides the stealth armour mod, allowing for faster silent movement and quicker assassinations. The Pioneer specialisation will give players the fast track armour mod, which increases the rate for acquiring experience points.
The other six specialisations - Engineer, Tracker, Rogue, Stalker, Pathfinder and Operator - will be made available in the following months. Microsoft did not mention whether the specialisations would be free or paid downloads.
Users can also gain access to all specialisations early by pre-ordering Halo 4 through select retailers or buying the game's limited edition.
Named 'Best Shooter' and 'Best Multiplayer' during Digital Spy's Best of E3 2012 awards, Halo 4 will be available exclusively on Xbox 360 from November 6 worldwide.
> Read our Halo 4 interview on multiplayer and narrative with 343 Industries
> Halo 4 multiplayer preview: WarGames is the fastest online Halo yet
Watch the weapons trailer for Halo 4 below: