Poe Soul (5e Equipment)
From D&D Wiki
Believed to be the literal soul of a poe, a poe soul usually takes a gaseous form that faintly glows violet or black. If left in an unsealed container for more than a few seconds, it will dissipate harmlessly into the air. As such one is usually contained in a vial or bottle.
As an action, you can drink the soul or administer it to an unconscious creature, then roll a d20. If the result of the d20 roll is even, the affected creature regains hit points equal to the result. If the result is odd, the affected creature takes necrotic damage equal to the result, but cannot be reduced below 1 hit point by this damage.
A creature immune to necrotic damage simply gains hit points equal to the rolled result.