The Reckoning Add-on for Call of Duty: Advanced Warfare has 10 achievements worth 250 gamerscore.
Defeat Oz in Descent.
Defeat Oz... again in Descent.
Complete Oz's Challenges in Descent.
Defeat Oz for the last time in Descent.
Kill Oz with a Blunderbuss in Descent.
Cross the water with a teleport grenade in Descent.
Punch Oz with a Goliath in Descent.
Punch 20 enemies with a Goliath in Descent.
Reach round 7 without anyone opening a door in Descent.
Kill 100 enemies behind you with the KL03-Trident