The Underdark Title update for Neverwinter has 8 achievements worth 350 gamerscore.
Kill the Balor boss in Prophecy of Madness 25 times
Kill the Illithilich boss in Throne of the Dwarven Gods 25 times
Get a Gold victory in the Infiltration variant of Throne of the Dwarven Gods
Earn Gold victory in Epic Demogorgon
Earn Gold victory in Demogorgon
Get a Gold victory in the Corruption variant of Throne of the Dwarven Gods
Get a Gold victory in the Madness variant of Prophecy of Madness
Get a Gold victory in the Incursion variant of Prophecy of Madness