Cloak of Tentacles

This cloak settles around your shoulders like a writhing creature, somehow simultaneously warm to the touch and icy cold against your skin.
Shimmering Skin. While wearing this cloak, you can use an action to expose its shimmering inner lining. Each creature within 10 feet of you and that can see you must make a DC 15 Wisdom saving throw. On a failed save, a creature is incapacitated until the end of its next turn. Once used, this property of the cloak can't be used again until the next dawn.
Writhing Tentacles. While wearing this cloak, you can use a bonus action to command the cloak to sprout four writhing tentacles for 1 minute. When a creature hits you with a melee attack while within 10 feet of you, one of the tentacles lashes out and makes an attack roll at your attacker with a +7 bonus. On a hit, the tentacle deals 2d10 bludgeoning damage then falls still, becoming inert. When the duration ends or once all four tentacles become inert, this property of the cloak can't be used again until the next dawn