Your enemy attacks when it appears to have an advantage, but you're ready for it.

Daily   ✦     Martial
Immediate Interrupt      Personal

Trigger: An enemy attacks you while it has combat advantage against you.

Effect: You gain temporary hit points equal to 3 + one-half your level. Until the end of your next turn, you do not grant combat advantage to the triggering enemy, and it grants combat advantage to you.

Published in Dragon Magazine 399.