Blood Sacrifice

The Sacrifice :  A target that can be touched makes a constitution saving throw (spell dc - X).  A willing target automatically fails this saving throw.  On a failed saving throw, the target loses X hit-points.  On a successful saving throw the target is unaffected but aware a spell was cast on them.

The Focus : A target within range (90ft) takes X D6 necrotic damage where X is the amount of damage done to the sacrifice.

Limitations :
X cannot exceed the amount of health the sacrifice has
X cannot exceed the casters spell DC
The Sacrifice and The Focus cannot be the same creature
The spell has no effect on constructs or the undead