The Nightmare Lash

[Requires Attunement]
You have a +1 bonus to attack and damage. On a
hit, you can expend one of your hit dice to deal an
additional 3d6 necrotic damage, regaining HP
equal to half the amount of necrotic damage dealt.
Curse: You want to remain bound, and feel a
compulsion to keep it. You can't willingly
unattune. If you lose possession of the whip, you
must spend their action recovering it. If at any
time the user of this whip has zero hit dice
remaining they die.