All or Nothing Coin

Wondrous Item, Rare

A large, brass coin. There is a simplistic face embossed on either side of the coin. On one side, the face smiles joyfully. On the other, it weeps madly.

Once per day, in place of any d20 roll you may flip the coin a single time. Heads is a Critical Success, Tails is a Critical Failure. However, you sense that there is always a chance that the magic within this coin could have exponentially good or dire effects. To flip or not to flip? That is the question.