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

Elemental Demise. If the elemental dies, its body crumbles to dark dust, leaving behind only equipment it was wearing or carrying.

Magic Resistance. The elemental has advantage on saving throws against spells and other magical effects.

Multiattack. The elemental makes four attacks.

Void Slash. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 19 (2d10+8) slashing damage plus 19 (2d10+8) force damage, and the target must succeed on a DC 25 Dexterity saving throw or have the Prone condition.

Void Blast. Ranged Spell Attack: +17 to hit, range 120 ft., one target. Hit: 26 (4d8+8) force damage, and the target must succeed on a DC 25 Strength saving throw or be pushed up to 20 ft. in any direction of the elemental's choice, including upwards.

Crystals From The Void. The elemental can create a void crystal - a shard of its essence - in an unoccupied space within 60 ft. of it. Each creature within 20 ft. of that space must make a DC 25 Dexterity saving throw, taking 22 (4d6+8) force damage on a failure, or half as much damage on a success. Whenever the elemental makes an attack roll, ability check, or saving throw, it adds an additional d4 to that roll for each void crystal within 30 ft. of it. Each other creature takes a cumulative -1 penalty to attack rolls, ability checks, and saving throws for each void crystal within 60 ft. of it.

A void crystal hovers 5 ft. above the ground, and can be attacked (AC 20, 80 hit points, immunity to poison and psychic damage). Furthermore, a creature can destroy a void crystal by using its action and succeeding on a DC 25 Intelligence (Investigation or Arcana) check while within 5 ft. of it. On a failure, or whenever an attack misses a void crystal, each creature within 20 ft. of it takes 9 (2d8) force damage, and the elemental gains temporary hit points equal to the total amount of damage taken from each creature.

The elemental can have up to four crystals at one time. If it creatures a fifth crystal, another crystal of the elemental's choice crumbles into a dark dust.

Hollow Resonance (Recharge 6). In response to a creature targeting the elemental with an attack, the elemental swaps places with a void crystal within 60 ft. of it. The void crystal becomes the target, instead.

The elemental can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time, and only at the end of another creature's turn. The elemental regains spent legendary actions at the start of its turn.

Empty Embrace. The elemental attempts to directly attack another creature's memories. The target must succeed on a DC 25 Constitution saving throw, or take 15 (2d6+8) psychic damage. The target has disadvantage on the saving throw if at least two void crystals are within 30 ft. of it. Furthermore, the damage increases by 3 (1d6) for each void crystal within 60 ft. of the target.

Crystal Burst. A void crystal of the elemental's choice explodes. Each other creature within 10 ft. of the exploding crystal must make a DC 25 Dexterity saving throw, taking 11 (1d6+8) piercing damage plus 15 (2d6+8) force damage on a failure, or half as much damage on a success. The crystal is then destroyed.

Move Crystal. The elemental moves a void crystal up to 30 ft. to an unoccupied space within 60 ft. of it.