Periapt of Wound Closure

Engraved with symbols of healing, this warm silver pendant prevents you from dying. * While wearing this pendant, you automatically stabilize when dying. You may still roll your Death _saving throw_ to try and roll a 20, but may only roll once on each of your turns and no more than three times. * Whenever you roll a Hit Die to regain hit points, you regain twice as many as normal.

Source: Level Up Advanced 5e · OGL-1.0a · 5.1