Vitality Singularity

You conjure forth a point of glimmering darkness within range.

On each of your turns until the spell ends, you may use your bonus action to move it up to 30ft. 

The Singularity has a pool of hitpoints, even though it can't be harmed, starting at 0 and with a maximum of 20. Whenever a creature within 30ft of the orb looses hit points, half of them are absorbed by the orb and go into the pool (or all of them if the creature took damage from a necromancy spell cast by you).

As an action your your turn, you may expend hit points from this pool and restore an equal amount of hit points to a creature within 15ft of the orb.

At higher Levels. For every slot level above 4th used to cast this spell, the orbs hitpoint maximum increases by 10 points.