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.
Note: See Hero Points for full details.
Advanced Player’s Guide. Copyright 2010, Paizo Publishing, LLC; Author: Jason Bulmahn.