You roll with the attack, taking a better position where you are bound to make your enemy pay.

Encounter   ✦     Primal
Immediate Reaction      Personal

Trigger: An enemy hits you with an attack while you are not adjacent to any of your allies.

Target: The triggering enemy

Effect: As a free action, you shift a number of squares equal to your primary ability modifier. You gain combat advantage against the target until the end of your next turn.

Published in Dark Sun Campaign Setting, page(s) 71.