As an action, you can use this item to make an attack roll against a creature within 15 feet of you.  The attack uses your Dexterity bonus and Proficiency with a whip allows you to add your Proficiency bonus to the attack roll.  If the attack hits, the creature is restrained and you cannot use this feature again until the creature is no longer restrained.  You can use an action to pull the restrained creature 10 feet towards you.  You can use a bonus action to tighten the lasso dealing 1d4 bludgeoning damage or to release a creature restrained by this item.  The restrained creature cannot be moved further than 15 feet from you while you hold the rope.  The creature must use an action to make a DC15 Strength (Athletics) check to free itself from the rope.  If the creature is more than one size class larger than you it is not restrained, you cannot pull it towards you, and it has advantage on the Strength check to free itself from the rope.