Wondrous Item (potion) , uncommon
This black stone phial has a tightly fitting stopper. The phial has three charges. As an action, you can fill the phial with blood taken form a living humanoid, or one that’s been dead no longer than 1 minute, and expend 1 charge. When you do so, the black phial transforms the blood into a potion of greater healing (heals4d4 + 4 hp . A creature who drinks this potion must succeed on a DC 12 Constitution saving throw or be poisoned for 1 hour.
The phial regains 1d3 expended charges daily at midnight. If you expend the phial’s last charge, roll a d20. On a 1, the phial crumbles into dust and is destroyed.