Chaos Elemental

Unstable Form. Defying the laws of nature takes its toll. At the start of the Chaos Elemental's turn it must succeed a DC 20 Con saving throw or lose 25 HP. If it took a hit that dealt 25 or more damage at once since its last turn, the saving throw is at disadvantage.

Multiattack. The Chaos Elemental makes two slam attacks and one Elemental Tide attack.

Slam. Melee Weapon Attack: +12 to hit, reach 10 ft., 1 target. Hit: 14 (1d12 + 7) bludgeoning damage. 

Elemental Tide. Special attack. Elements are assigned numbers 1 through 4. (Air=1, Earth=2, Fire=3, Water=4) Roll 2d4, then compare your results to the table below to determine the attack type. 

(1, 1) Whirlwind. The Chaos Elemental creates a 20ft wide, 40ft tall whirlwind. All creatures caught in the gust must make a DC 18 Strength saving throw. On a failure they take 3d8 bludgeoning damage, get flung 20ft in a random direction, and are knocked prone. On a save they take half damage and are not flung or knocked prone.

(1, 2) Dust Storm. The Elemental summons a storm or dust and stone to blind opponents. All creatures within 20ft of the Chaos Elemental must make a DC 18 Strength saving throw. On a failed save they take 3d8 bludgeoning damage, get flung 20ft in a random direction, and are blinded until the start of the elemental's next turn.

(1, 3) Smoke Cloud. The elemental exhales a 30-foot cone of smoke. Any creature in it must make a DC 18 Con save or be blinded, poisoned and unable to breathe while within the cloud. The area within the smoke becomes heavily obscured for 1 minute or until a strong wind blows it away.

(1, 4) Ice Fog. The elemental whips up a freezing fog in a 15ft radius sphere at a point it can see. All creatures in the fog must succeed on a DC 18 Con saving throw or take 3d8 cold damage and become paralyzed until the start of the elemental's next turn.

(2, 2) Earth Surge. The elemental sends forward a wave of surging earth in a 30ft cone. All creatures caught in it must make a DC 18 Dex saving throw. On a failure they take 2d8+7 bludgeoning damage and are knocked prone. On a success they take half damage and are not knocked prone.

(2, 3) Magma Splash. Ranged Weapon Attack. + 9 to hit, range 20/60 ft., one target.  1d10+4 bludgeoning and 3d6 fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

(2, 4) Mud Choke. The elemental creates a 15ft square of thick, grasping mud. All creatures in the area must make a DC 18 Strength saving throw. On a failure they take 3d8 bludgeoning damage and are grappled (escape DC 18). They must repeat the saving throw on subsequent turns, getting pulled further into the mud with each failure. After 3 failures they are dragged under the mud and become blinded, restrained, and unable to breathe. On a successful save the creature takes half damage and is not grappled.

(3, 3) Flamethrower. The elemental spits out a 40ft long, 10ft wide blast of fire. All creatures in range must make a DC 18 Dex saving throw, taking 4d6 fire damage on failed save, or half as much on a successful one.

(3, 4) Steam Scald. The elemental spits out steam and boiling water in a 30-foot cone. Each creature in it must make a DC 18 Con save, taking 4d6 fire damage or half as much on a successful save. Being underwater doesn't grant resistance against this fire damage.

(4, 4) Whelm. The elemental attempts to engulf any creatures within 5ft of it. Each creature must make a DC 18 Strength saving throw. On a failure, the creature is pulled into the elemental's body, takes 3d8 bludgeoning damage and is grappled (escape DC 18). At the start of each of the elemental's turns, each target grappled by it takes 2d8 bludgeoning damage. A creature within 5 feet of the elemental can pull a creature or object out of it by taking an action to make a DC 18 Strength check and succeeding.

The Chaos 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 Chaos Elemental regains spent legendary actions at the start of its turn.

Move. The Elemental moves up to its speed.

Slam. The Elemental makes a slam attack.

Elemental Burst (Costs 2 actions). The Elemental lets out a burst of elemental energy in a 10ft radius around it. Any creatures in range must succeed on a DC 18 Dex save or take 3d6 damage. Roll a d4 to determine the damage type.