Robe of Thunder
Wondrous item, rare (requires attunement)
This gray silk robe is printed with the image of boiling storm clouds. While wearing it, you have resistance to thunder damage.
As an action, you can speak its command word and you are surrounded by an invisible, faintly rumbling aura for 1 minute. When you take damage from a creature that is within 5 feet of you, the aura inflicts 2d6 points of thunder damage on your attacker.
Once used, this property of the robe can’t be used again until the next dawn.