Alien Mind. If a creature tries to read Yog-Sothoth thoughts or deals psychic damage to it, that creature must succeed on a DC 24 Intelligence saving throw or be stunned for 1 minute. The stunned creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Innate Spellcasting. Yog-Sothoth's spellcasting ability is Intelligence (spell save DC 24, +16 to hit with spell attacks). It can innately cast the following spells, requiring no material components:
At will: counterspell, detect magic, detect thoughts, dispel magic, eyebite, fireball, lightning bolt, shield
3/day each: chain lightning, create undead, dream, hold monster, mass suggestion, scrying
1/day each: foresight, gate, power word kill, prismatic spray
Legendary Resistance (3/Day). If Yog-Sothtoh fails a saving throw, it can choose to succeed instead.
Limited Magic Immunity. Yog-Sothoth can't be affected or detected by spells of 6th level or lower unless it wishes to be. It has advantage on saving throws against all other spells and magical effects.
Regeneration. Yog-Sothoth regains 40 hit points at the start of its turn. If Yog-Sothoth takes radiant damage, this trait doesn’t function at the start of its next turn. Yog-Sothoth dies only if it starts its turn with 0 hit points and doesn’t regenerate.
Teleport. As a bonus action, Yog-Sothoth can teleport up to 60 feet to an unoccupied space it can see.
Multiattack. Yog-Sothoth makes two Tentacle Whip attacks and uses its Corruption once. Yog-Sothoth can replace a Tentacle Whip attack with Extract Brain if it has a creature grappled.
Tentacle Whip. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 27 (4d10 + 10) slashing damage. If the target is a Large or smaller creature, it is grappled (escape DC 24), pulled into an unoccupied space within 5 feet of Yog-Sothoth, and must succeed on a DC 24 Intelligence saving throw or be stunned until this grapple ends. Yog-Sothoth can’t use the same tentacle whip on another target until this grapple ends. Yog-Sothoth has three tentacle whips.
Corruption. Yog-Sothtoh targets one creature it can see within 120 feet of it. The target must succeed on a DC 24 Constitution saving throw or take 31(4d6 + 10) necrotic damage and become corrupted for 1 minute.
A corrupted creature’s flesh twists in alien ways. The creature has disadvantage on attack rolls, its speed is reduced by half, and if it tries to cast a spell, it must first succeed on a DC 19 Intelligence check or the spell fails and is wasted. The corrupted creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Extract Brain. Melee Weapon Attack: +15 to hit, reach 10 ft., one incapacitated creature grappled by Yog-Sothoth. Hit: 66 (12d10) piercing damage. If this damage reduces the target to 0 hit points, Yog-Sothoth kills the target by extracting and devouring its brain.
Yog-Sothtoh 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. Yog-Sothtoh regains spent legendary actions at the start of its turn.
Tentacle Whip. Yog-Sothtoh makes one attack with its Tentacle Whip.
Regenerate (Costs 2 Actions). Yog-Sothoth regains 40 hit points. If Yog-Sothoth has taken radiant damage this turn, Yog-Sothtoh regains 20 hit points instead.
Mind Blast (Costs 3 Actions). Yog-Sothtoh magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 24 Intelligence saving throw or take 30 (5d8 + 10) psychic damage and be stunned 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.
Lair and Lair Actions
Yog-Sothoth's Lair
Yog-Sothoth makes its lair wherever they enter the material plane, corrupting their surrounding as eldritch energy seeps into the world around them, twisting its very essence. Buildings and walls of the lair undulate as air flows through them, as if the space were breathing.
Lair Actions. While within Yog-Sothoth's Lair, Yog-Sothoth can invoke the ambient magic to take lair actions. On initiative count 20 (losing initiative ties), Yog-Sothoth can take a lair action to cause one of the following effects; it can’t use the same effect two rounds in a row:
- Yog-Sothoth uses its Corruption action.
- A 30-foot-square area of ground within 120 feet of Yog-Sothoth sprouts tentacles until initiative count 20 on the next round. Any creature that starts or ends its turn in the area must succeed on a DC 23 Strength saving throw or be restrained. A creature can escape the tentacles with a successful DC 23 Strength (Athletics) or Dexterity (Acrobatics) check as an action.
- Each creature of Yog-Sothoth's choice that it can see within 120 feet of it must succeed on a DC 23 Wisdom saving throw or take 26 (4d12) psychic damage. Unless the target has immunity to psychic damage, its Intelligence score is reduced by 1d4 each time it fails the saving throw for this lair action. The target dies if its Intelligence score is reduced to 0. The reduction lasts until the target finishes a short or long rest.
Regional Effects
A region containing a passage to Yog-Sothoth's lair is warped in one or more of these ways:
- Plants and animals raised within 2 mile of the passage have twisted, aberrant forms.
- Creatures within 1 mile of the passage frequently feel as if something is crawling under their skin.
- If a humanoid spends at least 1 hour within 1 mile of the passage, that creature must succeed on a DC 22 Wisdom saving throw or descend into a type of madness (see “Madness of Yog-Sothoth” below). A creature that succeeds on this saving throw can’t be affected by this regional effect again for 24 hours.
If Yog-Sothoth dies, these effects fade away after 1d10 days.
Madness of Yog-Sothoth
If a creature goes mad in Yog-Sothoth's lair it gains a form of indefinite madness. Roll on the Madness of Yog-Sothoth table to determine the nature of this madness, which takes the form of a character flaw that lasts until cured.
Madness of Yog-Sothoth
| d6 | Flaw (lasts until cured) |
|---|---|
| 1 | “There’s an illithid parasite living in my brain!” |
| 2 | “I can feel myself evolving into an aberration.” |
| 3 | “Aberrations are the only natural things.” |
| 4 | “A part of me has become a conscious entity.” |
| 5 | “My opponents must bow down to a mind flayer!” |
| 6 | “Yog-Soth simply wants to unite all sentient creatures in collective consciousness. And I receive messages from the group mind!” |
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Posted Sep 19, 2022omg, i love this. i just wish it was lower level so my players could fight it
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Posted Mar 22, 2025Are they high enough level yet?