You have practiced using whips to perfection. Whips in your hands deal an additional 1d6 thunder damage. Additionally, you may as part of an attack attempt to grapple a hit creature. You can only make more whip attacks if the creature grappled is two or more size categories smaller than you. 

Attacks with a grappled creature doesn't have the finesse or reach properties. It also deals 1d6 +your strength modifier bludgeoning damage to the target and 1d8 bludgeoning damage to the grappled creature.