You can make your spells last twice as long.
Benefit: An extended spell lasts twice as long as normal. A spell with a duration of concentration, instantaneous, or permanent is not affected by this feat.
Level Increase: +1 (an extended spell uses up a spell slot one level higher than the spell’s actual level.)
Pathfinder RPG Core Rulebook. Copyright 2009, Paizo Publishing, LLC; Author: Jason Bulmahn, based on material by Jonathan Tweet, Monte Cook, and Skip Williams.