Blood Rush

You channel hemomantic magic to amplify your blows. Make a melee spell attack against one creature within 5 feet of you. On a hit, the target takes 1d8 necrotic damage. If your current hit points are below your hit point maximum, you also gain 1d4 temporary hit points, which last until the start of your next turn. 

The spell’s damage increases by 1d8 and the temporary hit points increases by 1d4 when you reach 5th level (2d8, 2d4), 11th level (3d8, 3d4), and 17th level (4d8, 4d4).