Halo 5: Guardians is getting another huge content update called Monitor's Bounty. On December 8, players can download a free update that includes new armor, skins, and weapons along with an option to join in-progress custom games, an eSports-esque Observer Mode, the ability to gift purchasable-only REQ packs to other players, and the "biggest Forge update ever seen in a Halo game."
Everything in the update is free except for the Voices of War REQ pack, which is $9.99 and features Spartan Buck, 031 Exuberant Witness, and Yabda the Merciless as multiplayer announcers.
Since it is one of the bigger updates, 343 will reveal the rest of the features on December 7, which will includes details on Forge, Canon Fodder, Warzone, and the Arena Matchmaking Playlists. For a complete rundown of the revealed details, read the post on Halo Waypoint.
[Source: Halo Waypoint]