Halo 4: Game of the Year Edition is coming out next week on October 8 for $39.99. Note that when we first learned about this package it was listed at $49.99, so this is a much better price now.
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.