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