Vampiric Demesne

When you cast this spell a dome of necrotic, sapping energy radiates out from you in a 15 foot radius. When you cast the spell you can designate any number of creatures you wish to be unaffected by the spell. 

When an affected creature enters the sphere for the first time on a turn or starts its turn there, it must make a Constitution saving throw. It suffers 4d6 necrotic damage on a failure or half as much on a successful save. You heal for half the damage done when this spell deals damage to a creature.

At Higher Levels. When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 per slot level over 4th.