Oh, It's On! - 10000 XP
Complete any Campaign Mission on Heroic or higher difficulty with the Mythic, Tilt, Storm and Tough Luck skulls.

Composition Chaos - 30000 XP
Complete Composer on Legendary difficulty with the Mythic, Tilt, Tough Luck and Thunderstorm skulls.

Spartan Ops

Harvesting Hunters - 20000 XP
Kill 5 Hunters.

Watchful Avenger - 10000 XP
Kill 30 Watchers.

War Games

Deadeye - 20000 XP
Kill 150 Players with a headshot.

Rolling Thunder - 10000 XP
Earn 20 Killing Spree medals.

Click here to see a complete list of this week's Weekly Challenges.