You’ve discovered the secret of stable transmutations
Benefit: Any transmutation spell you cast upon yourself has its duration increased by 2 rounds. Transmutation spells with an instantaneous duration are not affected by this trait.
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.