A character with the Whip Master feat gains proficiency with whips.

A Whip Master may use their bonus action to make a special maneuver with their whip. They may do this as long as the Whip Master is not carrying a shield or carrying a bulky load with their non-dominant hand. They may be carrying a lantern, purse, hat, idol, or similar easily portable object without impeding their ability to make this bonus attack. 

Special maneuvers include:

• Make a single melee attack against a target within range. This attack does 1d4 damage even if the whip is capable of delivering more damage, and adds the ability modifier the wielder usually applies to attacking with a whip for both the to-hit roll and the damage roll.
• Push or pull a small object: The whip wielder may attempt an ability check based on either Strength or Dexterity and their proficiency bonus to move a small or tiny object up to five feet.
• Wrap the whip around a target: The whip wielder attempts to entangle a target. Like grappling, when applied to a foe this is considered to be an attack for the purpose of things such as a Barbarian's rage feature, but does not deal any damage. Entangling a target requires a successful ability check using either Strength or Dexterity and the wielder's proficiency bonus, and may be opposed by an opponent's Athletics or Acrobatics check if the target is animate. If it is not animate, the DM should set a DC for the target. A horizontal tree-limb covered in rough bark would be DC 10. If the attempt is successful, the whip wielder may hang from the whip, swing on the whip, or attempt to grapple with the target. A target who has been entangled with the whip may use their action to attempt to break free, and will succeed on breaking free on a DC 10 Athletics or Acrobatics check. Any other circumstance that would remove the grappled or restrained conditions removes the entanglement. If a target has been entangled with a whip, they suffer disadvantage on attempts to resist subsequent grapple attacks by the Whip Master or their allies.

A Whip Master also gains the ability to use their reaction to make an opportunity attack with a whip that is wielded in their dominant hand when an opponent they can see enters their melee range.