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The God Brain
The God Brain squats malevolently in its roiling, vaporous broth. It is covered in sores and lesions, pus dissolving away into its tank while diligent mind flayers tend and sooth and operate – constantly. You feel its attention, like you’re being turned around in your own skin, pass over you and for a moment you hear its echoing madness in the patterns of your own thoughts and mind. The brain is in torment, madness, driven by palpable revenge and an endless thirst for forbidden lore.
Gargantuan Aberration, lawful evil
Armor Class: 11 (The God Brain is surrounded by an AC 22, 72 HP tank of transparent adamantine which is transparent to the God Brain’s powers, but must be broken before the God Brain can be attacked).
Hit Points: (20d12 + 180 – Roll when you encounter the God Brain to determine its current state of health)
Speed: 5 ft., swim 10 ft.
STR 30 (+10) DEX 10 (+0) CON 28 (+9) INT 23 (+6) WIS 18 (+4) CHA 24 (+7)
Saving Throws: Int +10, Wis +9, Cha +12
Skills: Arcana +11, Deception +12, Insight +14, Intimidation +12, Persuasion +12
Senses: Blindsight 480 ft., passive Perception 14
Languages: Understands Common, Deep Speech, and Undercommon but can’t speak, telepathy 5 miles
Overmind: The God Brain, while it sits in its lair, is aware of all its dedicated servants and can sense everything that they can sense and communicate with them in a network. So long as one servant can see or hear something, all can.
Mist Vibrations: To those it controls, its servants and some magical devices, the God Brain appears as a beacon in the mists. A fixed point to which its servants can always guide themselves, despite the confusion of the mists.
Closing the Border: The God Brain can electrify the mists and flood them with psychically active gases, effectively cutting them off and wiping the memories (Wisdom Save DC 18) of any who leave.
Life Support: The God Brain has reserves of spinal fluid it can use to heal itself from damage, and it is tended by mind flayers who can also engage in healing actions. The God Brain has 2d10 doses of spinal fluid, each of which can heal it for 1d12 Hit Points, once per turn as a bonus action. It’s tenders can expend an action to heal its sores and wounds with arcane devices and consoles, healing 1d6 Hit Points for each action (Move, Action, Bonus Action) they expend in tending it.
Creature Sense: The God Brain is aware of the presence of creatures within 20 miles of it that have an Intelligence score of 4 or higher. It knows the distance and direction to each creature, as well as each one’s intelligence score, but can’t sense anything else about it. A creature protected by a mind blank spell, a nondetection spell, or similar magic can’t be perceived in this manner.
Innate Spellcasting (Psionics): The God Brain’s innate spellcasting ability is Intelligence (spell save DC 19, spell attack +11). It can innately cast the following spells, requiring no components:
At will: detect thoughts, levitate, augury, blindness/deafness, enthrall, suggestion, zone of truth, comand.
4/day each: dominate monster, antipathy/sympathy, feeblemind, mind blank, forcecage, mirage arcane, project image, mass suggestion
Legendary Resistance (3/Day): If the God Brain fails a saving throw, it can choose to succeed instead.
Damage Vulnerability: The God Brain is vulnerable to poison damage.
Infirmity: The God Brain has disadvantage on Constitution Saves.
Magic Resistance: The God Brain has advantage on saving throws against spells and other magical effects.
Telepathic Hub: The God Brain can use its telepathy to initiate and maintain telepathic conversations with up to forty creatures at a time. The God Brain can let those creatures telepathically hear each other while connected in this way.
Tentacle: Melee Weapon Attack: +9 to hit, reach 30 ft., one target. Hit: (16d8 + 10) bludgeoning damage. If the target is a Huge or smaller creature, it is grappled (escape DC 23) and takes (4d8 + 5) psychic damage at the start of each of its turns until the grapple ends. The God Brain can have up to four targets grappled at a time.
Mind Blast (Recharge 5–6): The God Brain magically emits psychic energy. Creatures of the God Brain’s choice within 240 feet of it must succeed on a DC 18 Intelligence saving throw or take 32 (20d10 + 5) psychic damage and be stunned for 1 minute. A target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Psychic Link: The God Brain targets one incapacitated creature it can perceive with its Creature Sense trait and establishes a psychic link with that creature. Until the psychic link ends, the God Brain can perceive everything the target senses. The target becomes aware that something is linked to its mind once it is no longer incapacitated, and the God Brain can terminate the link at any time (no action required). The target can use an action on its turn to attempt to break the psychic link, doing so with a successful DC 18 Charisma saving throw. On a successful save, the target takes (12d6) psychic damage. The psychic link also ends if the target and the God Brain are more than 5 miles apart, with no consequences to the target. The God Brain can form psychic links with up to ten creatures at a time.
Sense Thoughts: The God Brain targets a creature with which it has a psychic link. The God Brain gains insight into the target’s reasoning, its emotional state, and thoughts that loom large in its mind (including things the target worries about, loves, or hates). The God Brain can also make a Charisma (Deception) check with advantage to deceive the target’s mind into thinking it believes one idea or feels a particular emotion. The target contests this attempt with a Wisdom (Insight) check. If the God Brain succeeds, the mind believes the deception for 1 hour or until evidence of the lie is presented to the target.
The God Brain 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 God Brain regains spent legendary actions at the start of its turn.
Tentacle: The God Brain makes a tentacle attack.
Break Concentration: The God Brain targets a creature within 120 feet of it with which it has a psychic link. The God Brain breaks the creature’s concentration on a spell it has cast. The creature also takes 4d4 psychic damage per level of the spell.
Psychic Pulse: The God Brain targets a creature within 480 feet of it with which it has a psychic link. Enemies of the God Brain within 10 feet of that creature take (12d6) psychic damage.
Sever Psychic Link: The God Brain targets a creature within 480 feet of it with which it has a psychic link. The God Brain ends the link, causing the creature to have disadvantage on all ability checks, attack rolls, and saving throws until the end of the creature’s next turn.
When fighting inside its lair, the God Brain can use lair actions. On initiative count 20 (losing initiative ties), the God Brain can take one lair action to cause one of the following effects; the God Brain can’t use the same lair action two rounds in a row:
The God Brain casts wall of force.
The God Brain targets up to four friendly creature it can sense within 480 feet of it. The target has a flash of inspiration and gains advantage on one attack roll, ability check, or saving throw it makes before the end of its next turn. If the target doesn’t or can’t use this benefit in that time, the inspiration is lost.
The God Brain targets one creature it can sense within 480 feet of it and anchors it by sheer force of will. The target must succeed on a DC 18 Charisma saving throw or be unable to leave its current space. It can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
The territory within 20 miles of the God Brain is altered by the creature’s psionic presence, which creates one or more of the following effects:
Creatures within 20 miles of an God Brain feel as if they are being followed, even when they are not.
The God Brain can overhear any telepathic conversation happening within 20 miles of it. The creature that initiated the telepathic conversation makes a DC 18 Wisdom (Insight) check when telepathic contact is first established. If the check succeeds, the creature is aware that something is eavesdropping on the conversation. The nature of the eavesdropper isn’t revealed, and the God Brain can’t participate in the telepathic conversation unless it has formed a psychic link with the creature that initiated it.
Any creature with which the God Brain has formed a psychic link hears faint, incomprehensible whispers in the deepest recesses of its mind. This psychic detritus consists of the God Brain stray thoughts commingled with those of other creatures to which it is linked.