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This gelatinous green monster has a vaguely octopoid head and a face that is a mass of feelers. It has titanic claws, bat-like wings, and a massive, corpulent form.

Huge aberration, chaotic evil

Armor Class 19 (natural armor)

Hit Points 250 (20d12 + 120)

Speed 40 ft., fly 60 ft., swim 40 ft.

29 (+9) 13 (+1) 23 (+6) 21 (+5) 22 (+6) 20 (+5)

Saving Throws Str +16, Con +13, Int +12, Wis +13, Cha +12

Skills Athletics +16, Yog-Sothothery +13

Damage Immunities cold, poison, psychic

Condition Immunities charmed, poisoned, prone

Senses blindsight 30 ft., darkvision 60 ft., passive Perception 16

Languages Aklo, telepathy 300 ft.

Challenge 21 (33,000 XP)

Special Traits

  • Body Control. The starspawn can contort, stretch, or compress its body to an extraordinary degree. This has the following effects: Amorphous. The starspawn can move through a space as narrow as 5 feet wide without squeezing.
  • Immovable. The starspawn has advantage on ability contests and saving throws against effects that would move it.
  • Prodigious Reach. As a bonus action, the starspawn can extend the reach of one of its weapon attacks by up to 300 feet until the start of its next turn.
  • Immortality. The starspawn doesn’t need to eat or breathe and doesn’t age.
  • Innate Spellcasting (Psionics). The starspawn’s spellcasting ability is Intelligence (spell save DC 20, +12 to hit with spell attacks). It can innately cast the following spells, requiring no components:
    • At will: dream, feeblemind, sending
    • 3/day each: suggestion (can target creatures through dream), wish (duplicate spells only)
    • 1/day: gate
  • Legendary Resistance (3/day). If the starspawn fails a saving throw, it can choose to succeed instead.
  • Regeneration. The starspawn regains 30 hit points at the start of its turn. If the starspawn is damaged by a weapon with an Elder Sign, this trait doesn’t function at the start of the starspawn’s next turn. The starspawn dies only if it starts its turn with 0 hit points and doesn’t regenerate. If the starspawn starts its turn at 0 hit points for the tenth round in a row, it does not regain consciousness even when it has at least 1 hit point until it spends 24 hours with at least 1 hit point.
  • Star Travel. The starspawn can survive and fly in space.
  • Unfathomable Mind. A starspawn’s mind is overwhelming in its power and alien structure. When a creature initiates mental contact with a starspawn (including via telepathy) or attempts to learn the starspawn’s emotions or thoughts (even unsuccessfully), it learns no information except what the starspawn intentionally shares and it must make a DC 20 Intelligence saving throw. An aberration, celestial, elemental, fiend, or creature that has attempted this saving throw (successfully or not) against any starspawn’s Unfathomable Mind since the last dawn automatically succeeds. On a failed save, the creature that contacted the starspawn’s mind takes 26 (4d12) psychic damage and is stunned until the end of the starspawn’s next turn. The starspawn can use its Overwhelming Telepathy legendary action to use this trait offensively.


  • Multiattack. The starspawn can use its Frightful Presence. It then makes three attacks: one with its tentacles and two with its claws.
  • Claw. Melee Weapon Attack: +16 to hit, reach 30 ft., one target. Hit: 18 (2d8 + 9) slashing damage.
  • Tentacles. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 42 (6d10 + 9) bludgeoning damage and a large or smaller target is grappled (escape DC 17). Until this grapple ends, the target is restrained. The starspawn has six tentacles, each of which can grapple one target.
  • Frightful Presence. Each creature of the starspawn’s choice that is within 300 feet of the starspawn and aware 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, the creature is immune to the starspawn’s Frightful Presence for the next 24 hours.
  • Shed Spawn (1/Year). If the starspawn has at least 76 hit points, it loses 75 hit points and sheds a portion of its own mass to spawn a larval starspawn (see below) in an open space within 30 feet. Roll initiative for the larval starspawn, which has its own turns.

Legendary Actions

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

  • Claw. The starspawn makes a claw attack.
  • Overwhelming Telepathy. The starspawn telepathically reveals unfathomable concepts to a target creature within 300 feet or that it is currently contacting via dream or sending. The target must make a saving throw against the starspawn’s Unfathomable Mind trait.
  • Tentacles (Costs 2 Actions). The starspawn attacks with its tentacles.


Starspawn are a highly intelligent species from another part of the universe, and many of their abilities derive from the differing fundamental natural laws from whence they come. They can change their proportional size and symmetry at will. For instance, a starspawn could push most of its mass into its wings to give it the needed size to fly or cause a single tentacle to grow to supreme length— as its body collapses in behind it—to reach a victim at a great distance. As needed, it could also sprout a sensory organ at the end of the tentacle or reach around a target to attack from more than one direction.

In their standard state, starspawn have four limbs and two wings, as well as a face dominated by a mass of feelers.

They can alter the proportions of this shape as they please but always adhere to the same basic structure.

Starspawn do not have brains as humans understand them—instead, every part of their body is a sort of nerve or brain cell. Thus, the larger a starspawn, the more intelligent, because its sheer volume increases its intelligence and abilities. Their minds are wholly alien, full of psionic and magic potential. Great Cthulhu is, technically, just another starspawn, but his enormous size reflects the fact that he is also among the oldest and most powerful.

Section 15: Copyright Notice

Sandy Petersen’s Cthulhu Mythos, © 2018, Petersen Games; Authors: Sandy Petersen, David N. Ross, James Jacobs, Arthur Petersen, Ian Starcher.