Necrotic Claw

Melee Spell Attack: +9 to hit, range 5 ft., one target. Hit: 14 (2d8 + 5) slashing damage plus 14 (4d6) necrotic damage.

Killing Joke

The grim jester tells an ancient, nihilistic joke to one creature it can see within 60 feet of it. The target must succeed on a DC 17 Wisdom saving throw or fall prone in a fit of laughter, becoming incapacitated and unable to stand up for 1 minute. A creature that fails this saving throw by 5 or more is reduced to 0 hp instead. The incapacitated target can repeat the saving throw at the end of each of its turns, taking 14 (4d6) necrotic damage on a failed save or ending the effect on itself on a success.

Spellcasting

The grim jester casts one of the following spells, requiring no components and using Charisma as the spellcasting ability (spell save DC 17): At will: disguise self, grease 3/day each: magic mouth (as an action), mirror image 1/day each: mislead, seeming