The Infernal Descent Title update for Neverwinter has 6 achievements worth 55 gamerscore.
Land on the single floating column outside the back of the Infernal Citadel.
Complete the Dungeon: The Infernal Citadel
Defeat All Rare Fiends in Vallenhas
Save 200 Citizens from Fiends in Vallenhas
Restore Glyphworks 20 times
Fire a catapult 50 times