Listening to the Bone and Sickle podcast and I had an idea!
Red Cap Tooth
Wonderous item, rare
You have a gnarled, decayed tooth of a vile recap. The tooth though fills you with the luck of the Fey. As a reaction, you can reroll a single d20 you just rolled and are forced to take the second result, even if worse. You may do this two times per day, but if you attempt this a third time, the tooth crumbles to dust.