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