Gloves of Soul Catching

From Candlekeep Mysteries, page 169.

Description
Wondrous item, legendary (requires attunement)

Your Constitution score is 20 while you wear these gloves. This property of the gloves has no effect on you if your Constitution is already 20 or higher.

After making a successful unarmed strike while wearing these gloves, you can use the gloves to deal an extra 2d10 force damage to the target, and you regain a number of hit points equal to the force damage dealt. Alternatively, instead of regaining hit points in this way, you can choose to gain advantage on one attack roll, ability check, or saving throw you make before the end of your next turn.