Cloak of Deception
From Tales of Maj'Eyal
Obtained from the starting 'boss' Necromancer, who is a required combat for any undead (Ghoul or Skeleton) character. While worn, the undead character will be disguised in towns; removing the cloak will make neutral NPCs in town attack you!
Notes
SPOILER ALERT
Undead characters who have access to Sher'Tul Fortress may spend 10 fortress energy to make the effect of the cloak permanent, allowing using any other cloak while remaining disguised. (If the character was not wearing the cloak at the time, they will need to put on and take off the cloak to apply the permanent effect.)