Transfusion

Targetting a creature within range, the caster siphons life essence from the targeted creature, manifesting as a stream of blood flowing from the target.

The target must succeed on a Constitution Saving throw, or take 1d6 + Spellcasting Modifier physical damage on a failed save, or half that on a success.

You regain 1d4 Blood Charges if the taget failed its save, and half that on a success. If the target died from the damage done, regain 4 charges.

At higher levels you can drain more essence from your enemies. You may drain an additional target at level 5, level 11, and level 17. The essence may be drained from a single target, or from a different one for each additional drain. Each additional target may also provides an additional 1d4 Blood Charges per drain, including a full 4 Charges if the target dies.

If a target dies while drained by more than of your siphons, it counts as a single instance, and only provides 4 charges.