It was a large, baggy, hooded cape or mantle that could be drawn about the wearer and concealed all they wore underneath. It was made of a dull, gray fabric that seemed unnatural.
When they successfully joined the Shadowcloaks guild every member was granted their own shadowcloak. They had to protect their cloak, and if they lost it to an enemy, they had to reclaim it within three days or be killed.
A shadowcloak granted a variety of powers useful to a Shadowcloak's trade. For one, it had the same power as a cloak of elvenkind, giving them increased ability to hide, to the point of being practically invisible. It also served as a cloak of protection +2.
The wearer also gained infravision, the ability to see in the dark. However, this came with the side effect of limiting their normal vision in well-lit areas, slowing their ability to react according to the light level.
Meanwhile, the shadowcloak had a hidden curse ensured a thief or spy's loyalty to the guild. They could not remove the shadowcloak without express permission from the Night Hood himself, except to change clothes or bathe. Plus, any Shadowcloak who left Calaunt wearing one lost a little health each day, and this could not be healed by any means without returning to Calaunt. Thanks to this, the Night Hood was unconcerned with his minions fleeing the city. Nothing short of a wish spell would allow a shadowcloak to be removed.