Charybdis

False Appearance. While the charybdis remains motionless, it is indistinguishable from a Huge rock formation.

Mimicry. The charybdis can mimic any sounds it has heard, including voices. A creature that hears the sounds can tell they are imitations with a successful DC 16 Wisdom (Insight) check. Creatures that fail this check have disadvantage on detecting or resisting illusions created by the charybdis.

Mental Plunder. The first time a creature moves within 30 feet of the charybdis, the charybdis initiates an Intelligence contest. On a failure, the charybdis learns personal details about the creature's life, like languages, fears, hopes, dreams, and surface thoughts. The creature also has disadvantage on detecting and resisting all illusions created by the charybdis on a failure. On a success, a creature is immune to the Mimicry and Mental Plunder traits of all charybdi for 24 hours.

Multiattack. The charybdis makes two Mind Grasp attacks.

Mind Grasp. Melee Attack Roll: +8, reach 30 ft. Hit: 7 (1d6 + 4) Bludgeoning damage plus 7 (2d6) Psychic damage, and the target is Grappled (escape DC 18) and pulled 30 feet toward the charybdis.

Spellcasting. The charybdis casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 16):

At Will: Comprehend Languages, Detect Magic

3/Day Each: Enthrall, Major Image, Animate Dead

2/Day Each: Bestow Curse, Hallucinatory Terrain, Dominate Person

1/Day Each: Contagion, Danse Macabre

Consume. Strength Saving Throw: DC 17, one Large or smaller creature that is Grappled by the charybdis (the charybdis can swallow 2 Large creatures, 8 Medium or Small creatures, or 32 Tiny creatures). Failure: 18 (3d8 + 5) Piercing damage, the target is swallowed, and the Grappled condition ends. While swallowed, the creature is Blinded and Restrained, it has total cover against attacks and other effects outside the charybdis, and it takes 10 (3d6) Acid damage at the start of each of the charybdis' turns.

If the charybdis dies or a swallowed creature uses its action on a successful DC 15 Strength (Athletics) or Dexterity (Acrobatics) check, a swallowed creature is no longer Restrained by it and can escape from the corpse by using 15 feet of movement, exiting Prone within 5 feet.