Double or Nothing

Ability Score Increase. Increase your Strength, Dexterity, Intelligence, Wisdom, or Charisma score by 1, to a maximum of 20.

The Wager. When you make an Attack roll, an Ability Check, a Saving Throw, or roll damage for an attack or spell, you can declare you are going "All In" before any dice are rolled. Choose Odds or Evens. If you wager on a damage roll, you roll a single d20 to resolve the wager before rolling the actual damage dice.

Payout. If the natural result on the d20 matches your choice (for an Attack roll, the roll must also result in a hit), you gain a Payout based on the roll type:
Attack Roll: The attack becomes a Critical Hit.
Ability Check or Saving Throw: The d20 roll is treated as a 20.
Damage Roll: The attack or spell deals its maximum possible damage (treat all of its damage dice as having rolled their maximum value).

Bust. If the natural result on the d20 does not match your choice, or if an Attack roll misses despite matching your choice, you suffer a Bust based on the roll type:
Attack Roll: The attack misses. Until the start of your next turn, Attack rolls against you have Advantage.
Ability Check or Saving Throw: The d20 roll is treated as a 1. You have Disadvantage on the next Ability Check or Saving Throw you make before the start of your next turn.
Damage Roll: The attack or spell deals its minimum possible damage (treat all of its damage dice as having rolled a 1).

You can use this feature a number of times equal to your Proficiency Bonus. You regain all expended uses when you finish a Long Rest.

Changelog

1. [v1.1] Added Strength, Dexterity, Intelligence, Wisdom, and Charisma to the Ability Score Increase.