Doomcaller Eye

When slain, the eyes of a doomcaller harden into gems worth 2000 gp each. When a creature holding one of these gems makes an attack roll, ability check, or saving throw, they can consume it to improve their fortunes. After the roll has been made, but before the GM has announced the result of the roll, the player can expend one gem and reroll the roll. Once done, the player must use the new result, the gem shatters and becomes worthless.

Notes: (Taken from doomcaller statblock from Grimhollow: Monster Grimoire published by Ghostfire Gaming)