As your foes move to flank, you deftly step aside, then engulf them in your dragon breath.

Encounter   ✦     Martial
Immediate Reaction      Personal

Trigger: An enemy moves into a position where it flanks you.

Effect: You shift 1 square and use your dragon breath as a free action, gaining a bonus to the damage roll equal to one-half your level, even if you have already used your dragon breath in this encounter.

Published in Player's Handbook Races: Dragonborn, page(s) 18.