CTHULHU

Amphibious. Cthulhu  can breathe air and water.

Mucous Cloud. While underwater, Cthulhu  is surrounded by transformative mucus. A creature that touches Cthulhu  or that hits it with a melee attack while within 5 feet of it must make a DC 14 Constitution saving throw. On a failure, the creature is diseased for 1d4 hours. The diseased creature can breathe only underwater.

Probing Telepathy. If a creature communicates telepathically with Cthulhu , Cthulhu learns the creature's greatest desires if Cthulhu  can see the creature.

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

Spellcasting. Cthulhu is a 21st level spellcaster. His spellcasting ability is Intelligence (spell save DC 23, +14 to hit with spell attacks). Cthulhu the Risen has the following spells prepared.

Cantrips (At-Will): Eldrich Blast, Shape Water, Thaumaturgy, detect thoughts, levitate 

1st Level Spells (7 Slots): Detect Magic, Magic Missile, Shield, dominate monster

2nd Level Spells (6 Slots): Blindness/Deafness, Darkness, Hold Person, suggestion 

3rd Level Spells (5 Slots): Blink, Counterspell, Fireball, Wall of Water, speak with dead

4th Level Spells (5 Slots): Dimension Door, Evard's Black Tentacles, Greater Invisibility, Watery Sphere

5th Level Spells (5 Slots): Bigby's Hand, Contact Other Plane, Hold Monster, Telekenisis, dream

6th Level Spells (4 Slots): Disintegrate, True Seeing, mass suggestion 

7th Level Spells (3 Slots): Finger of Death, Teleport, Whirlwind, plane shift,

8th Level Spells (2 Slots): Antimagic Field, Control Weather, Feeblemind, Power Word Stun, Tsunami, sunburst

9th Level Spells (1 slot): Meteor Swarm, Storm of Vengeance, Wish, 

Palingenesis. When Cthulhu is reduced to 0 hit points or killed, only his physical shell is destroyed. It will reform at a later point.

Regeneration. Cthulhu regains 15 hit points at the start of his turn.

Siege Monster. Cthulhu deals double damage to objects and structures.

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

Magic Weapons. Cthulhu's weapon attacks are magical.

Aura of Madness. All creatures within 600 feet of Cthulhu must succeed a DC 16 WIS save or become frightened. Any creature that succeeds the save cannot be affected by Cthulhu in this way again for 24 hours.

Multiattack. Cthulhu makes three tentacle attacks.

Tentacle. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or become diseased. The disease has no effect for 1 minute and can be removed by any magic that cures disease. After 1 minute, the diseased creature's skin becomes translucent and slimy, the creature can't regain hit points unless it is underwater, and the disease can be removed only by heal or another disease-curing spell of 6th level or higher. When the creature is outside a body of water, it takes 6 (1d12) acid damage every 10 minutes unless moisture is applied to the skin before 10 minutes have passed.

Tail. Melee Weapon Attack: +9 to hit, reach 10 ft. one target. Hit: 15 (3d6 + 5) bludgeoning damage.

Enslave (3/Day). Cthulhu  targets one creature it can see within 30 feet of it. The target must succeed on a DC 14 Wisdom saving throw or be magically charmed by Cthulhu until Cthulhu dies or until it is on a different plane of existence from the target. The charmed target is under Cthulhu’s control and can't take reactions, and the Cthulhu and the target can communicate telepathically with each other over any distance.

Whenever the charmed target takes damage, the target can repeat the saving throw. On a success, the effect ends. No more than once every 24 hours, the target can also repeat the saving throw when it is at least 1 mile away from dread Cthulhu .

Bite. Melee Weapon Attack: +17 to hit, reach 5 ft., one target. Hit: 23 (3d8 + 10) piercing damage. If the target is a Large or smaller creature grappled by Cthulhu, that creature is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside Cthulhu, and it takes 42 (12d6) acid damage at the start of each of Cthulhu's turns.

If Cthulhu takes 50 damage or more on a single turn from a creature inside him, Cthulhu must succeed on a DC 25 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of Cthulhu. If Cthulhu dies, a swallowed creature is no longer restrained by him and can escape from the corpse using 15 feet of movement, exiting prone.

Stomp. Cthulhu stomps on a creature. They must make a dc 20 dexterity saving throw. They take 69 bludgeoning damage on a failed save, and half as much on a successful one.

Psionic Storm. Cthulhu magically creates three psionic bolts, each of which can strike a target Cthulhu can see within 120 feet of him. A target must make a DC 23 Dexterity saving throw, taking 44 (8d10) psychic damage on a failed save, or half as much damage on a successful one.

Call of Cthulhu (recharge 6). Cthulhu lets out a mind splitting roar. All creatures that can hear him must make a dc 20 wisdom saving throw or take 110 psychic damage and go insane for 1 week.

Cthulhu can take 4 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 aboleth regains spent legendary actions at the start of its turn.

Detect. Cthulhu  makes a Wisdom (Perception) check.

Tail Swipe. Cthulhu makes one tail attack.

Psychic Drain (Costs 2 Actions). One creature charmed by Cthulhu takes 10 (3d6) psychic damage, and Cthulhu  regains hit points equal to the damage the creature takes.

Tentacles. Cthulhu makes two tentacle attacks.

Psionic Storm (Costs 2 Actions). Cthulhu uses Psionic Storm.

Recharge (Costs 3 Actions). Cthulhu attempts to recharge Call of Cthulhu. He rolls a d100. On a 60 to 100, the attack recharges.

Call of Cthulhu. Cthulhu uses Call of Cthulhu.

• If Cthulhu’s mythic trait is active, it can use the options below as legendary actions for 1 hour

•  Withering curse (Costs 2 Actions). Cthulhu spreads withering dust. Any creature within 60 feet of Cthulhu must succeed a dc17 constitution  saving throw or gain one level of exhaustion.

• Coral Growth (Costs 2 Actions). Each creature within 10 feet of Cthulhu must make a DC 25 Dexterity saving throw, taking 13 (3d8) slashing damage on a failed save, or half as much damage on a successful one. Until the start of its next turn,and it gain a +2 bonus to AC