Venenum Mortis

Having been taken in by the Elder of Hollows Lumina, her affectionate nature as a parental figure does not just intend to keep you safe but also to support you throughout your journey in the Twilight.
In order to do so, she has granted you access to a rudimentary fragment of her powers, allowing for you to draw vials of her blood and black mist for personal use.

After finishing a long rest, you receive a mix of vials, containing either Undying Mist, or Reaper Cells.
The total amount of vials that you receive is equal to your proficiency bonus, and you may determine the distribution of vials yourself when you do receive them.

Undying Mist
A vial containing black mist that is brimming with the life force your mother has reaped from others.

As a bonus action, you may open it and apply it to a creature within 5ft reach of yourself.
The creature then rolls all their remaining hit dice and heals for that amount.

Reaper Cells
A vial of poison containing the blood and rapidly duplicating cells of your mother.

As a bonus action you may apply this blood to a piece of ammunition or weapon that does either slashing or piercing damage remains potent until delivered through a wound or is washed off.
On a hit, the target must make a Constitution Saving Throw against your Poison DC from your Poisoner's Proficiency feature.
On a failure, it takes an amount of damage equal to all its hit die rolled at once as magical poison damage. On a success it takes half as much.

This does not include their Constitution Modifier and damage dealt cannot exceed 300.