Rare Weapon (Flail), Reach, Requires Attunement

• You can cast the Vicious Mockery (DC 13) cantrip with this item. It deals 2d4 psychic damage. 

Sinister Mockery. The flail’s head probes into the mind of its victims, filling their mind with the most stinging of mockeries.
When you hit an enemy with an attack made with this weapon, you can use your reaction to cast Vicious Mockery on the target.
Immediately after you hit a creature with an attack of opportunity, you can cast Vicious Mockery at the target as part of the reaction. 

Contagious Laughter. As an action, you can go into a mad and debilitating fit of laughter, making you incapacitated. Any creature within 5 feet of you when you use the effect, or ends their turn in the area while this feature is active, must make a DC 13 Wisdom saving throw, suffering from the effects of the Hideous Laughter spell on a failure, and becoming immune to this feature for 1 minute on a success. 

You can end this effect at the end of each of your turns.
When you end the effect, all creatures affected by it immediately succeed on the saving throw 
Cackling Curse (Secret). If you use Contagious Laughter more times per long rest than is your proficiency bonus, or if you keep it active for at least an entire minute without interruption,
you become unable to end the feature until you finish your next long rest. After you finish your next long rest, you also gain 1 level of exhaustion.