Death's Shadow

This black garnet amulet is carved into the shape of a bird's skull and is adorned with several dark feathers. At its center is a single phoenix feather that serves as a catalyst for this strange talisman's necromantic magic. While wearing this amulet, you are immune to necrotic damage.

Shadow Form: When you are reduced to 0 hit points while wearing this amulet, a shadowy version of yourself rises from your unconscious body. You control this form, which has your equipment and statistics. It has 100 temporary hit points and resistance to all damage that isn't force, psychic, or radiant. The shadow form can't move more than 60 feet from your body. The shadow vanishes after 1 minute or when it loses all its temporary hit points. If the shadow survives for the duration, it returns to your body and causes you to regain a number of hit points equal to the shadow's remaining number of temporary hit points. If the shadow is defeated, the amulet is destroyed and you immediately fail 2 death saving throws. While your shadow form is defending you, your unconscious body is covered by an impenetrable veil of shadow. While covered in this way, you can't be interacted with: you are immune to all damage, don't make death saving throws, can't regain hit points, and can't be affected by spells or magical effects. A creature can use an action to make a DC 30 Strength check, moving the covered body up to 10 feet on a success. Once this property has been used, it can't be used again until 7 days have passed.