Deny the Reaper

When the reaper's touch is imminent, your unyielding oath sets your soul ablaze. Upon failing your third Death Saving Throw, you may channel this power to become an incarnation of your sacred vows.

Oathkeeper. For 1 minute, you transcend mortal limits:

You are restored to your maximum hit points and gain Truesight. Your spell slots and your Lay on Hands feature are fully replenished. Lay on Hands automatically heals your or an ally within 30 feet at the start of each your turns without needing a bonus action. Your form grows radiant. You gain resistance to all damage types. You shed bright light for 30 feet and dim light for 30 feet more.

Sacred Crusader. Your weapon becomes enchanted with pure radiance.

Attacks with your weapon deal an additional 1d8 radiant damage. Your Divine Smite feature deals and additional 2d8 radiant damage. Whenever you hit a target with a weapon attack imbued with your Divine Smite feature you can force the target to make a make a Charisma saving throw. On a failure, if it has committed acts against your oath, it becomes Branded For Justice. Branded creatures have their movement speed halved if trying to move away from you.

If damage would reduce a Branded creature to hit points lower than your Charisma score, the creature instead dies.

Purifying Presence. Your Auras range doubles and gains the following:

At the start of each of your turns, remove one negative condition from up to two willing creature within 60 feet. Whenever a Fiend, Undead, Aberration or Monstrosity starts its turn within your Aura it must succeed on a Charisma saving throw, taking 2d8 radiant damage on a success, or half as much on a failure.

The End:

When the effect of this boon expires you fall unconscious but stable until you finish a long rest. Upon waking, you gain 4 levels of exhaustion. You lose the ability to cast 4th level or higher spells and the ability to use this Boon. You can regain access to these spells and use of this Boon after completing a quest that is appropriate for your Oath.

(Optional). Your oath transforms into a Geas cast by your deity. Breaking it results in instant death.