Vampiric Aura

This spell creates a 15' radius Aura around the caster marked by glowing Necrotic energy.  

Any enemy creatures that come within range for the first time or starts there turn inside the aura must make a Constitution saving throw.  Upon a fail, they receive 3d6 Necrotic damage.  The caster also heals for half of the damage dealt to the 1st enemy damaged each turn.

At higher levels.  The damage increases by 1d6 for every spell level above 3rd, and you can heal for half the damage done to an additional enemy for every spell level above 3rd.