Co-developed by Certain Affinity and 343 Industries, the Defiant Map Pack will feature two multiplayer maps and one Firefight arena for 800 Microsoft Points (£6.80 / $10).
Condemned will be set on a space station orbiting Reach, and will support six to 12 players in Team Slayer, Team Objective and Free for All game types.
Set on the planet of Reach is Highlands, which is a large training area set in a woodland, and will cater for eight to 16 player game types such as Big Team Battle, Team Objective and Team Slayer.
Finally, Firefight map Unearthed will have humans and Covenant forces fight for control over a Titanium mine and refinery.
The map pack will also include several Achievements worth 150 Gamerscore.
Click the 'play' button below to watch a trailer.