Frenzied Berserker Utility 12Deathless Frenzy
For a time, your anger can stave off even death.
Immediate Interrupt Personal
Trigger: You drop to 0 hit points or fewer and don’t die
Effect: Until you regain hit points, you are dying but don’t fall unconscious because of that condition. If you fail a death saving throw, you fall unconscious, and this effect ends.
Published in Player's Handbook 2, page(s) 64.