Blood Siphon

You touch a creature with the tip of your finger and attempt to
siphon their life force to strengthen your own. Make a melee spell
attack against a target, with a successful attack dealing 1d4 necrotic
damage and granting you half of the damage dealt as temporary hit
points.
The spell’s damage increases by 1d4 when you reach 5th level
(2d4), 11th level (3d4), and 17th level (4d4).