Graceful Movement. The Sugarplum Fairy's movement speed is not slowed by difficult terrain or the affects of her Plum Pudding.

Misty Dance. As a bonus action, the Sugarplum Fairy can teleport up to 30 feet to an unoccupied space she can see. She can use this ability between weapon attacks or other actions she takes.

Dance of the Sugarplum Fairy. Once at the end of her turn, the Sugarplum Fairy makes a DC 22 performance check. If she succeeds, any character who saw her dance must make a DC 14 Wisdom saving throw. On a fail, that character starts twirling and dancing under her spell and can take no actions on their turn and must use their movement to go a random direction decided by a d8. The effect falls off at the end of her next turn.

Legendary Resistances (3/Day). If the Sugarplum Fairy fails a saving throw, it can choose to succeed instead.

Multiattack. The Sugarplum Fairy can make three ice dagger melee or ranged attacks.

Ice Dagger Melee. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) piercing damage. On a hit, the character makes a DC15 con saving throw or takes 1d4 additional cold damage and is slowed by 5 movement speed as the cold seeps in. 

Ice Dagger Ranged. Ranged Weapon Attack: +8 to hit, range 20/60 ft., 1 target. Hit: 12 (2d6 + 5) piercing damage. 

Pirouette. As an action the Sugarplum Fairy can choose a spot she can see within 30 feet and teleport to it. Any creature within 10 feet must make a DC 14 Wisdom saving throw or take 25 (7d6) Psychic damage as they become enthralled with her performance. A creature takes half damage on a save.

The Sugarplum Fairy can take 3 Legendary Actions, choosing from the options below. Only one legendary option can be used at a time, and only at the end of another creature's turn. She regains spent legendary actions at the start of her turn.

Grande Jete (Costs 1 Action). The Sugarplum Fairy can move up to her movement speed without provoking opportunity attacks.

Dagger (Costs 1 Action). The Sugarplum Fairy makes one dagger melee or ranged attack.

Plum Pudding (Costs 2 Actions). The Sugarplum Fairy can cause the floor of the lair to turn puddingy. Each creature must make a DC 14 Con save to avoid sinking in. On a fail, the creature's movement is reduced by 10 until the start of the Sugarplum Fairy's turn when the floor returns to normal.