Phoenix Feather

Wondrous item, uncommon (requires attunement) Price: 500-750 gp | low sentimentality

The fires that once erupted from this phoenix’s feather have long extinguished, but the feather is still hot to the touch.

Paid

After you attune to the feather, the first time you would drop to 0 hit points as a result of taking damage, you instead regain hit points equal to your maximum hit points and the feather bursts into flame and is destroyed.

Overpaid

When the feather is destroyed, a sphere of fire erupts from the feather. Creatures within 30 feet of the feather that aren’t attuned to it must make a DC 12 Dexterity saving throw. Targets suffer 4d6 fire damage on a failed save, or half as much damage on a successful one.

Source: The Gray Merchant of Asphodel