As Things Were Meant To Be - Quest Reward Feat

This feat is awarded with a number of charges chosen by the DM, (default is 1). 

By expending 1 charge, you can add an additional +1 modifier to any attack roll, ability check, or saving throw you make. Uniquely, this modifier effectively changes the number rolled on the dice, allowing you to turn a natural 1 into a natural 2, or a natural 19 into a natural 20. You can choose to add this modifier before or after rolling the d20, but this must be done before you learn the outcome of the roll.

The only way to regain charges is to be awarded this feat by your DM again.