To others, it seems that you always have a bit of luck around you.
Prerequisite: Hero’s Fortune.
Benefit: Whenever you spend a hero point to reroll a die roll or to grant yourself a bonus before a die roll is made, there is a chance that the hero point is not spent. Whenever you spend a hero point, roll a d20. If the result is greater than 15, the hero point is not spent. You cannot use this Feat when you use the cheat death Hero Point option.
Advanced Player’s Guide. Copyright 2010, Paizo Publishing, LLC; Author: Jason Bulmahn.