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