You were a prisoner or slave in a city on the Elemental Planes, such as the cruel efreet’s City of Brass on the Plane of Fire or a dwarven city on the Plane of Earth. When you escaped that city, you had to use your captors’ weapons and magic against them in addition to your sheer wits, and you learned how to find weaknesses in their natural resistances.
At character creation, select acid, cold, electricity, or fire (once chosen, this selection can’t be changed). Once per day as a swift action, you can choose a single creature that is within 30 feet of you and within your line of sight; treat that creature’s resistance against your chosen energy as 5 lower than its normal energy resistance for 1 round. This ability has no effect if the creature has no resistance to the chosen energy or if the creature has immunity to the chosen energy.
Pathfinder Player Companion: Elemental Master’s Handbook © 2017, Paizo Inc.; Authors: John Compton, Eleanor Ferron, Mikko Kallio, Jason Keeley, Isabelle Lee, and Christopher Wasko.