Cthulhu

AC 24 (natural armor)
HP 585 (30d20+270; bloodied 292)
Speed 60 ft., fly 200 ft., swim 60 ft.

Proficiency +9; Maneuver DC 25
Skills Arcana +18, History +18, Insight +19, Intimidation +17, Investigation +18, Nature +18, Perception +19, Religion +18
Damage Resistances acid, fire, lightning, necrotic, thunder; bludgeoning, piercing, and slashing from magical or adamantine weapons
Damage Immunities cold; bludgeoning, piercing, and slashing from nonmagical weapons not made from adamantine
Condition Immunities charmed , diseased , frightened , paralyzed , petrified
Senses darkvision 200 ft., truesight 60 ft. passive Perception 29
Languages Deep Speech; telepathy 300 ft.

Immortality. If Cthulhu is killed, its body immediately fades away into a noxious cloud of otherworldly vapor that fills an area out to its reach. This cloud blocks vision as fog cloud , but can’t be dispersed by any amount of wind. Any creature in this area must succeed at a DC 27 Constitution saving throw or be poisoned for as long as it remains in the cloud and for an additional 1d10 rounds after it leaves the area. Cthulhu returns to life after 2d6 rounds, manifesting from the cloud and restored to life via resurrection, but has 5 levels of fatigue and cannot take both a move and action in the same turn. At the end of each of its turns, Cthulhu makes a DC 20 Constitution saving throw to reduce its fatigue level by 1. If slain again while suffering from this effect, Cthulhu reverts to vapor form again and its essence fades away after 2d6 rounds, returning to its tomb in R’lyeh until it is released again.

Innate Spellcasting. Cthulhu’s innate spellcasting ability is Wisdom (spell save DC 27; spell attack +19). It can innately cast the following spells, requiring no material components:

Constant: freedom of movement , true seeing
At will: astral projection , control weather , dispel magic , dream , phantasmal killer , sending , suggestion , teleport
3/day: antipathy, feeblemind , gate , plane shift , weird
1/day: power word stun , symbol , wish

Insanity. Any creature that attempts to interact directly with Cthulhu’s thoughts (such as a detect thoughts or telepathy) must succeed at DC 27 Wisdom saving throw or gain an indefinite mental stress effect . When using its telepathy to communicate Cthuhlu doesn’t activate this feature unless it spends an action to focus its mind on one opponent. In addition, unlike normal any mental stress effects caused by Cthulhu are cumulative and each resolves separately.

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

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

Nightmare Haunting. While on the Ethereal Plane or Material Plane, Cthulhu magically touches a sleeping humanoid on the Material Plane. A protection from evil and good spell cast on the target prevents this contact, as does a magic circle . As long as the contact persists, the target has dreadful visions. If these visions last for at least 1 minute, the target gains no benefit from its rest, and its hit point maximum is reduced by 7 (2d6). If this effect reduces the target’s hit point maximum to 0, the target dies and its soul travels to R’lyeh. The reduction to the target’s hit point maximum lasts until removed by the greater restoration spell or similar magic. For every 5 minutes the visions last, the target gains a short-term mental stress effect . For every 10 minutes the visions last, the target gains a long-term mental stress effect.

Non-Euclidean. Cthulhu does not exist wholly in the physical world, and space and time strain against its presence. Its apparent and actual position are never quite the same, and creatures have disadvantage on attack rolls against it. A creature with truesight does not have disadvantage but a DC 17 Wisdom saving throw is needed each time it looks at Cthulhu. On a failure, the creature gains a short-term mental stress effect. On a failure by 5 or more, the target also gains a long-term mental stress effect.

Regeneration. Cthulhu regains 30 hit points at the start of its turn if it has at least 1 hit point.

Starflight. Cthulhu can survive in the void of outer space and flies through the cosmos at incredible speeds. The exact travel time varies from one trip to the next, but a trip within a solar system normally takes Cthulhu 2d6 hours, and a trip beyond normally takes 2d6 days (or more, at the Narrator’s discretion).

ACTIONS

Multiattack. Cthulhu can use its Mind-Shattering Presence. It then makes six attacks: two with its claws and four with its tentacles.

Claws. Melee Weapon Attack: +17 to hit, reach 40 ft., all targets in a 10-foot square (any creature in the area whose AC is equal to or less than the result is hit). Hit: 26 (4d8+8) slashing damage plus the target is grappled (escape DC 25).

Tentacles. Melee Weapon Attack: +17 to hit, reach 30 ft., one target. Hit: 26 (4d8+8) bludgeoning damage plus the target is grappled (escape DC 25). A target that takes 20 or more damage makes a DC 27 Wisdom saving throw or gains a short-term mental stress effect . On a failure by 10 or more, the target gains a long-term mental stress effect instead.

Mind-Shattering Presence. Each creature of Cthulhu’s choice within 300 feet of it Wisdom saving throw or die from terror. A creature immune to fear that fails its saving throw is stunned 1d4 rounds instead of killed. On a success, a creature is immune to Cthulhu’s Mind-Shattering presence for 1 minute.

Swallow. Cthulhu makes one tentacle attack against a Medium or smaller creature it is grappling . If the attack hits, that creature takes the tentacle’s damage and 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. At the start of each of Cthulhu’s turns the swallowed creature takes 42 (12d6) necrotic damage and makes a DC 27 Wisdom saving throw . On a failure, the creature gains one short-term mental stress effect . On a failure by 5 or more, the creature also gains a long-term mental stress effect, and on a failure by 10 or more the creature gains an indefinite mental stress effect as well.

If Cthulhu takes 30 damage or more on a single turn from a creature inside it, Cthulhu must succeed on a DC 15 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 it and can escape from the corpse using 15 feet of movement, exiting prone.

BONUS ACTIONS

Summon Alien. Cthulhu can use a bonus action to conjure any aberration of CR 12 or lower. The creature appears in an unoccupied space that Cthulhu can see within 100 feet. This feature otherwise functions as conjure elemental but does not require Cthulhu’s concentration .