tempest blade

You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects,takes an additional 1d6 lightning damage and cannot take reactions until the end of their next turn.

at higher levels

The extra lighting damage increases by 1d6 at 5th,11th and 17th levels