Sapping Sting

Necromancy cantrip
Casting Time: 1 action
Range: 30 feet
Components: V, S
Duration: Instantaneous
Spell List: Arcane, Communion

You sap the vitality of one creature you can see in range. The target must succeed on a Constitution saving throw or take 1d8 necrotic damage and you gain half the damage as temporary hit points.
At higher levels. This spell's damage increases by 1d8 when you reach 5th level (2d8), 11th level (3d8), and 17th level (4d8).