Desperation (5e Feat)
From D&D Wiki
Your will to live bolsters you as your thread unwinds. You gain the following benefits:
- Increase your Constitution by 1.
- When you are subjected to a Melee attack of any type that would reduce you to 0 Hit Points or less and have a melee weapon in hand, make a DC 15 Constitution saving throw. On a successful save, you can use your reaction to shield yourself with your weapon and add a +2 to your AC, possibly blocking the attack.