Taken from Dragon magazine issue 300, this 3.5 edition spell, updated for 5th edition, this gruesome spell can be added to your game to make that villain just a tad more terrifying!
This spell has no effect on constructs or undead and can only be cast on a creature that is bleeding
when this spell is cast the target must make a (DC 13) constitution saving throw. Upon a failure the targets blood springs into an unholy life as tendrils of blood leave the targets body and leap through the air attempting to attach themselves to the caster ( the tendrils can go through cracks and under doors, as well as bending around objects, but not through solid objects) upon reaching the caster the blood will be absorbed into their body and give the caster temporary hit points equal to half the damage dealt
This spell deals 3D6 necrotic damage on a failed constitution saving throw an NO damage on a successful saving throw
also, on a failed saving throw anytime the target of this spell takes any pricing or slashing damage while this spell is in effect they take an additional 1D4 necrotic damage, this will also give the caster of the spell temporary hit points equal to half the damage dealt by the 1D4