Eldritch whip

This spell creates a whip of crackling energy wielded by the caster. You can use the attack action with this weapon (meaning if you have extra attack you may attack twice)  dealing either lightning or fire damage. Melee spell attack, 1d6 damage of chosen type on a hit. You can also attempt to grapple a creature with this whip. 
The spells damage increases by 1d6 and levels 5, 11, and, 17