Strength before Death

Starting at 18th level, your fighting spirit can delay the grasp of death. If you take damage that reduces you to 0 hit points and doesn't kill you outright, you can use your reaction to delay falling Unconscious, and you can immediately take an extra turn, interrupting the current turn. While you have 0 hit points during that extra turn, taking damage causes death saving throw failures as normal, and three death saving throw failures can still kill you. When the extra turn ends, you fall Unconscious if you still have 0 hit points.

Once you use this feature, you can't use it again until you finish a long rest.