Chaos Elemental

Chaos Form. The elemental ignores movement restrictions caused by the elements. At the start of each of its turns, each creature within 15ft of it takes 7(2d6) fire damage plus 7(2d6) acid damage plus 7(2d6) cold damage plus 7(2d6) lightning damage plus 7(2d6) poison damage plus 7(2d6) thunder damage. A creature also takes this damage when it touches the elemental or hits it with a melee attack.

Dual Creature. This creature is also considered a Fiend when determining creature types. 

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

Siege Monster. The elemental deals double damage to objects and structures.

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

Magic Weapons. The elemental's weapon attacks are considered magical.

Vaporize. Any standing or running water or ice no deeper than 10ft within 15ft of the elemental is instantly turned into steam at the end of the elemental's turn. Additionally, any elemental made of water or ice dies within 2 turns while within 15ft of the elemental. 

Multiattack: The elemental makes five attacks, one Fling attack, one Scorch attack, one Slam attack, one Smash attack, and one Elemental Fury attack.

Fling: Melee weapon attack, +15 to hit, reach 10ft, one target. Hit 17(2d8+8) bludgeoning damage plus 4(1d8) thunder damage, and the target must succeed on a DC 20 Constitution saving throw or be pushed 30ft in a direction of the elemental's choice and Deafened until the end of the target's next turn. Unsecured objects of size Huge or smaller are pushed automatically. 

Scorch: Melee weapon attack, +15 to hit, reach 10ft, one target. Hit 22(5d8) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the flames, the target takes 11(2d10) fire damage at the start of each of its turns. 

Slam: Melee weapon attack, +15 to hit, reach 20ft, one target. Hit 17(2d8+8) bludgeoning damage plus 4(1d8) cold damage, and the target is grappled by a watery arm(escape DC 20). Until this grapple ends, the target is Restrained. The elemental can have more than one target Restrained at a time. 

Smash: Melee weapon attack, +15 to hit, reach 20ft, one target. Hit 21(3d8+8) bludgeoning damage plus 4(1d8) acid damage, and the target must succeed on a DC 20 Strength saving throw or be knocked Prone. 

Elemental Fury: Ranged weapon attack, +15 to hit, range 200/400ft, six targets. Hit: the target takes  44(8d8+8) damage of one of the damage types of the elemental's choosing: acid, cold, fire, lightning, poison, or thunder. The elemental cannot choose the same damage type twice. 

Transmute(Recharge 5-6): The elemental alters the form of each creature and object within 30ft of it to confuse the elements. Ground, water, and air in the area are transformed into slurry: heavily obscured water that is difficult terrain. Each creature and object within 30ft of the elemental must make a DC 20 Constitution saving throw. On a failed save, a target takes 39(6d12) force damage and is Stunned until the end of its next turn. ON a successful save, a target takes half as much damage and suffers no ill effects. 

The elemental can take 3 legendary actions, choosing from the options below. Only one legendary action 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. 

Destructive Wrath: The elemental makes two melee attacks using different weapons. The attacks must be made against objects, structures, or Constructs.

Howl of Terror(Cost 2 Actions): The elemental roars with primordial fury that resonates into the soul. Each creature of the elemental's choice within 120ft of it must succeed on a DC 20 Wisdom saving throw or become Frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, it is immune to the elemental's Howl of Terror for the next 24 hours. 

Primordial Flow(Cost 2 Actions): The elemental moves its speed without making opportunity attacks. During this movement, it can enter hostile creatures spaces and it can move through a space as narrow as 1 inch wide without squeezing, but it can't end its movement in such a place. The first time it enters a creature's space during this movement, the creature takes damage equal to twice the amount stated in the elemental's Chaos Form trait.