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Image promptlarge floating aberrant brain creature, pallid folded flesh, many staring eyes, trailing nerve tendrils, dungeon walls flexing and reshaping as its body, shifting stone corridors, psychic light lances, isolating maze, sickly grey-pink flesh, damp black masonry, crimson psychic glow from eyes and wall-seams, alien hovering menace, dark fantasy, grimdark, painterly digital art, dramatic chiaroscuro lighting, muted desaturated palette with corrupted-crimson accents, weathered post-Cataclysm atmosphere, intricate high detail, cinematic composition

Labyrinth Mind

Large Aberration, Lawful Evil
CR 17ControllerDungeon / Structure
AC 19
HP 264 (23d10 + 138)
Speed 20 ft., Fly 40 ft. (hover)
STR
12
+1
save +1
DEX
16
+3
save +9
CON
22
+6
save +12
INT
26
+8
save +14
WIS
20
+5
save +11
CHA
18
+4
save +4
Skills Arcana +14, Insight +11, Perception +11
Resistances Psychic; Bludgeoning, Piercing, Slashing (nonmagical)
Immunities Charmed, Frightened, Prone
Senses Truesight 120 ft.; Passive Perception 21
Languages Deep Speech, Common; telepathy 120 ft.

Traits

Legendary Resistance (3/Day).

Living Labyrinth. The walls of the structure the Labyrinth Mind occupies are an extension of its body. Within 120 feet, with no Bonus Action required, it can reshape any wall/corridor (create a new wall, remove an existing one). This is used to separate enemies.

Maze Sense. Knows the location of every creature inside the structure.

Actions

Multiattack. Makes two Mind Lance attacks and uses one Shift Corridor.

Mind Lance. Ranged Attack Roll: +14, range 120 ft. Hit: 27 (4d10 + 8) Psychic damage, and the target makes a DC 22 Intelligence save. Failure: The target's Concentration is broken and it can't take Reactions until the end of its next turn.

Shift Corridor. The Labyrinth Mind targets two enemies it can see within 120 feet. Each makes a DC 22 Charisma save. Failure: The target is teleported to another part of the labyrinth (chosen by the Labyrinth Mind; up to 300 feet away). The target appears Prone.

Sanity Fracture (Recharge 5–6). Intelligence Saving Throw: DC 22, every enemy within 60 feet.

  • Failure: 49 (11d8) Psychic damage, and the target has the Stunned condition for 1 minute. The target can repeat the save at the end of each of its turns.
  • Success: Half damage.

Legendary Actions (3/Round)

Reshape. Alters the walls using Living Labyrinth; an enemy makes a DC 22 DEX save, taking 20 (3d12) Bludgeoning damage on a failure (struck by a wall).

Mind Lance (Costs 2). Makes one Mind Lance attack.

Isolate (Costs 3). Uses Shift Corridor.

How to Use

The dungeon itself is the monster. This is Tier 4's most clever design.

Shift Corridor splits the party — the Fighter ends up in one room, the Wizard 300 feet away. Then the Labyrinth Mind hunts them one by one.

Key

Find it. The Labyrinth Mind exists physically somewhere. Use Truesight/Detect Thoughts to find its location. And burn its Legendary Resistance — there are 3, then Hold Monster works.