Syphon energy

The touch of your shadow-wreathed hand can siphon life force from others to heal your wounds. Endless darks shadowy hands snake down and wrap around a target. Make a melee spell attack against a creature within your reach. The enemy takes 3D6 necrotic damage. On success, Endless Dark squeezes the energy out of his enemies and into his own life force  regaining the same amount of damage into his health pool  

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.