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 Wolves of Mars" quest.
Complete "The Court of Oryx" quest.
Complete "The Nightstalker's Trail" quest.
Complete "The Sunbreakers' Challenge" quest.
Complete "The Taken King" quest.
Complete "The Stormcaller's Path" quest.