You discovered a secret that enhances the energy of some spells.
Benefit: Once per day as a free action, when you cast a spell that deals acid, cold, electricity, or fire damage, you can enhance that spell with volatile energy. When you do, it deals 1d4 points of extra damage of the same energy type.
Pathfinder Roleplaying Game: Ultimate Campaign. © 2013, Paizo Publishing, LLC; Authors: Jesse Benner, Benjamin Bruck, Jason Bulmahn, Ryan Costello, Adam Daigle, Matt Goetz, Tim Hitchcock, James Jacobs, Ryan Macklin, Colin McComb, Jason Nelson, Richard Pett, Stephen Radney-MacFarland, Patrick Renie, Sean K Reynolds, F. Wesley Schneider, James L. Sutter, Russ Taylor, and Stephen Townshend.