Thunder Absorbing Tattoo
Wondrous item (tattoo), very rare (requires attunement)
Produced by a special needle, this magic tattoo features designs that emphasize one color (orange).
Tattoo Attunement
To attune to this item, you hold the needle to your skin where you want the tattoo to appear, pressing the needle there throughout the attunement process. When the attunement is complete, the needle turns into the ink that becomes the tattoo, which appears on the skin.
If your attunement to the tattoo ends, the tattoo vanishes, and the needle reappears in your space.
Damage Resistance
While the tattoo is on your skin, you have resistance to thunder damage.
Damage Absorption
When you take thunder damage, you can use your reaction to gain immunity against that instance of the damage, and you regain a number of hit points equal to half the damage you would have taken. Once this reaction is used, it can’t be used again until the next dawn.
Source: Tasha’s Cauldron of Everything p. 119