BlessedDeath

BlessedDeath has an innate connection to the dead and dying. As such, at the end of each turn, the BlessedDeath carrier can use a bonus action to gain an accurate understanding of how close or far a chosen target is to death.

BlessedDeath converts necrotic damage to healing, and healing effects into radiant damage. 

Kiss of Death. Choose an ally target: Both the ally target and the BlessedDeath carrier make CON saving throws. If the BlessedDeath carrier rolls higher, the ally target takes 1d8 Necrotic damage. If the ally rolls higher, they are healed for 1d12. A target can't be affected by Kiss of Death more then once a day, regardless of the result.

BRRRRAAAAAIIIIINS!!  If the BlessedDeath carrier is put to half or less max hp, it can use this reaction: Move upto 15ft. towards the closest hostile target and make a melee attack roll, on a hit the target will take (3d6 + 4) necrotic damage, and the BlessedDeath carrier will be healed for half as much as damage dealt. If this reaction kills a target, it will automatically recharge, otherwise it cannot be used again until the next dawn.