Vesper Primer+Immediate Actions+Twist Away
Your quick reflexes and dexterous movements make up for your lack of stamina.
Prerequisite: Evasion.
Benefit: While you are wearing light armor or no armor, if you are forced to attempt a Fortitude saving throw, you can use an immediate action to instead attempt a Reflex saving throw (at the same DC). If you succeed at this saving throw and the attack has a reduced effect on a successful save, you avoid the effect entirely.
Whether the saving throw is successful or not, you are staggered until the end of your next turn.