Aldren's Amulet of Preserved Essence

A disc of clouded glass in a brass frame, worn on a braided leather cord.
While attuned to this amulet, you gain a +1 bonus to AC.

Preservation. When you're reduced to 0 hit points while wearing this amulet, you can make a DC 12 Constitution saving throw. On a success, you drop to 1 hit point instead. Once this property is used, it can't be used again until you finish a long rest.

[A disc of clouded, faintly milky glass in a plain brass frame, hung on a braided leather cord. Something moves faintly within the glass when tilted. Mood: quiet, clinical, faintly unsettling.]

Notes: Bonus: Armor Class, Preservation. When you're reduced to 0 hit points while wearing this amulet, you can make a DC 12 Constitution saving throw. On a success, you drop to 1 hit point instead. Once this property is used, it can't be used again until you finish a long rest