The The Taken King Add-on for Destiny has 10 achievements worth 250 gamerscore.
Complete "The Sunbreakers' Challenge" quest.
Complete the King's Fall Raid.
Complete the King's Fall Raid (Heroic).
Complete "The Taken King" quest.
Complete "The Stormcaller's Path" quest.
Complete "The Court of Oryx" quest.
Complete "The Old Hunger" quest.
Complete the "Echoes of Oryx" quest.
Complete "The Nightstalker's Trail" quest.
Complete "The Wolves of Mars" quest.