Relentless Rage

Your Rage can keep you fighting despite grievous wounds. If you drop to 0 Hit Points while your Rage is active and don't die outright, you can make a DC 10 Constitution saving throw. If you succeed, your Hit Points instead change to a number equal to twice your Barbarian level. Each time you use this feature after the first, the DC increases by 5. When you finish a Short or Long Rest, the DC resets to 10.