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Cortex Siphon - AI-generated fantasy Monster

Cortex Siphon

Scholars call it a cortex siphon, a psionic devourer, or simply the bliss-brain. It is not a giant brain, but a cunning aberration whose central nervous mass has expanded into a torso-sized organ capable of terrifying psychic output. The closer it comes to death, the more violently its mind blooms, flooding nearby creatures with euphoric static that both weakens their resolve and makes its own powers surge. Black-market psionics prize its brain, called a Psionic Cortex, because a living harvest preserves the active bliss field. Once the creature dies, that sensation collapses, leaving only a pale shell and a far less potent prize.

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LargeAberration(Psionic aberration)CR CR 23Typically neutral evil

Cortex Siphon

AberrationPsionicControllerUrban HorrorLegendaryHarvestablePsychic
HP360AC19SPDwalk 30 ft., fly 40 ft. (hover)CR23ArcanaInsightPerceptionStealthDeception
STR
14
DEX
18
CON
26
save
INT
22
save
WIS
20
save
CHA
24
save
Magic Resistance. The cortex siphon has advantage on saving throws against spells and other magical effects.
Telepathic. The cortex siphon can communicate telepathically with any creature it can see within 120 feet.
Psionic Euphoria Aura. Creatures that start their turn within 20 feet of the cortex siphon must succeed on a Wisdom saving throw or feel a narcotic wave of psychic comfort. On a failure, the creature cannot take reactions until the start of its next turn, and the first time it hits with an attack before then, it deals 7 fewer damage. A creature that fails by 5 or more is also charmed until the end of its turn. A creature that succeeds is immune to this aura for 24 hours.
Death-Pressure Empowerment. When the cortex siphon is at or below half its hit points, its psychic attacks deal an extra damage, and it adds 1 to the save DC of its psionic abilities. Its mind becomes more volatile and more potent as it approaches death.
Living Cortex Harvest. If a creature attempts to harvest the cortex siphon's brain while it is alive, it must use specialized equipment. A successful Medicine check or relevant tool check is required to extract the Psionic Cortex without ruining its euphoric charge. If the creature dies first, the charge rapidly dissipates.
Multiattack. The cortex siphon makes two Mind Lance attacks, or one Mind Lance attack and one Cortex Rend attack.
Mind Lance. Ranged Spell Attack: to hit, range 240 ft., one target. Hit: 32 () psychic damage, and the target must succeed on a Intelligence saving throw or have disadvantage on the next attack roll, ability check, or saving throw it makes before the end of its next turn as intrusive thoughts spiral through its mind.
Synaptic Overload. The cortex siphon targets up to three creatures it can see within 90 feet. Each target must make a Intelligence saving throw. On a failure, a target takes 27 () psychic damage and is stunned until the end of its next turn. On a success, it takes half damage and is not stunned.
Neuroleptic Shriek. The cortex siphon releases a scream of bliss and terror in a 60-foot cone. Each creature in that area must make a Wisdom saving throw. On a failure, a creature takes 35 () psychic damage and is incapacitated until the start of its next turn. On a success, it takes half damage and is not incapacitated. A creature that fails the save also has its speed reduced to 0 until the end of its next turn.
Cortex Rend. Melee Spell Attack: to hit, reach 10 ft., one target. Hit: 22 () psychic damage, and the target must succeed on a Constitution saving throw or suffer psionic hemorrhage, taking 13 () psychic damage at the start of each of its turns until it or another creature uses an action to staunch the damage with a Medicine check or magical healing.
Thought Slip. When hit by a spell or psionic effect, the cortex siphon can halve the damage from that effect and immediately move up to 10 feet without provoking opportunity attacks. It can do this only if it is below half its hit points.
Skitter Through Thought. The cortex siphon moves up to half its speed without provoking opportunity attacks. If it moves at least 10 feet, one creature of its choice within 10 feet of where it ends this movement must succeed on a Wisdom saving throw or be rattled by psychic afterimages, giving it disadvantage on opportunity attacks until the end of that creature's next turn.
Mind Lance (Costs 2 Actions). The cortex siphon makes one Mind Lance attack.
Euphoria Pulse (Costs 3 Actions). The cortex siphon unleashes a concentrated wave of ecstatic psionic pressure. Each creature of its choice within 20 feet must succeed on a Intelligence saving throw or take 18 () psychic damage and be unable to take reactions until the end of its next turn.
Cantrips
Innate PsionicsPsionics— The cortex siphon's spellcasting ability is Intelligence, and its spell save DC is 21 with +13 to hit with spell attacks. It can innately cast the following spells, requiring no components: at will: detect thoughts, message, mage hand; 3/day each: dimension door, hypnotic pattern, telekinesis; 1/day each: dominate monster, feeblemind.
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