It's going to include the game itself, the Champions Bundle, the War Games Map Pass (which includes the Majestic, Castle, and Crimson map packs), and 15 pieces of in-game and avatar content from the Halo 4 campaign.
The re-release will also be giving us a cloaked Master Chief avatar item based on the Halo 5 trailer that was teased during E3 this year. Cute, I guess.
There won't be a public beta of the latest Halo: The Master Chief Collection update
7:00 PM on 02.10.2015