Mercy and Malice

"Let them feel every lash, every curse, every touch of malice that they first dealt to me." —Ragnarok,
the Lost One
As a bonus action before your standard
attack with this weapon you can select a
d4, d6, d8, or d10 to add to your damage
roll as necrotic damage, in exchange for
the same amount of HP as the chosen die's
top face value.