Fight For Your Life (5e Feat)

Sheer determination and resilience allow you to temporarily overcome mortal wounds. As a reaction when any effect reduces you to 0 hit points, you remain conscious, but must now Fight For Your Life. While in this state, damage received does not incur a failed death saving throw. You can move up to 10ft, and this movement doest not invoke Attacks of Opportunity.

Pick a target that has a minimum CR equal to your player level divided by 4, rounded up. You may make one weapon attack or cast one spell that has a casting time of 1 action and requires an attack roll against this target (provided you have any spell slots remaining). If this attack reduces the target to 0 hit points, you suffer one level of exhaustion, and you gain 1 hit point plus temporary hit points equal to your Hit Die. This does not expend any of your Hit Dice.

If you choose to not Fight For Your Life, or fail to reduce the target to 0 hit points, you do not suffer any levels of exhaustion, you fall unconscious, and must make death saving throws as usual.