The thrill of the kill is enough to shake off any ill effects.

Daily   ✦     Healing, Martial
Free Action      Personal

Trigger: You score a critical hit or reduce an enemy to 0 hit points

Effect: You spend a healing surge and regain additional hit points equal to your Constitution modifier. You make a saving throw against each effect on you that a save can end, and you gain a bonus to the saving throws equal to your Constitution modifier.

Published in Martial Power 2, page(s) 16.