These are undead who guard a locked door and chest in the Tomb of the Betrayers in the Merchant District of Neverwinter. Every time an adventurer approaches the locked door without using the trick to keep it open, two of these will spawn.
Draped in ancient finery, this cadaverous figure stands silent sentry over the tombs. Its baleful yellow eyes seem to hold more intelligence than most undead.
In the original campaign, there are very few places where it is possible to "farm" experience points. The place where these spawn is one of those few places. For a solo adventurer who has Onan of Tyr in his party, it's possible to gain several levels relatively quickly by repeatedly triggering these enemies to appear and executing them.
Solo adventurer XP amounts for each kill (with only Onan of Tyr in the party and in the same room):
Level 7: 152xp
Level 8-9: 126xp
Level 10-11: 91xp
Level 12: 74xp
If these have any damage reduction, it is currently unknown. They are susceptible to piercing and slashing damage. They don't have any concealment. However, they are immune to sneak attacks and critical hits.
They have 25AC and get one attack per round with 9AB. They use the Taunt skill and have access to Power Attack.