You steel yourself for battle, girding yourself against your foe's initial assault.

Encounter   ✦     Psionic
Free Action      Personal

Trigger: An attack hits or misses you for the first time during an encounter

Effect: Until the end of your next turn, you gain resistance to all damage equal to 3 + your Wisdom modifier.
Level 11: Resist 6 + your Wisdom modifier.
Level 21: Resist 9 + your Wisdom modifier.

Published in Player's Handbook 3, page(s) 44.