Vampiric Blade

As part of the action used to cast this spell, you must make a melee attack against one creature within the spell's range, otherwise the spell fails.  On a hit, the target suffers the attack's normal effects, and you absorb part of the creature's life essence.  The creature takes additional necrotic damage equal to your spellcasting ability modifier, and the creature cannot regain hit points until the start of your next turn.

If a creature is reduced to zero hit points by this attack, you gain 1d4 temporary hit points.

At 5th level, the melee attack deals an extra 1d6 necrotic damage to the target on a hit, and the temporary hit points gained increases to 2d4. The damage dealt increases by 1d6 and temporary hit points increase by 1d4 at 11th level (2d6 and 3d4) and 17th level (3d6 and 4d4)