Urophion

False Appearance. While the Urophion remains motionless, it is indistinguishable from a normal cave formation, such as a stalagmite.

Grasping Tendrils. The Urophion can have up to six tendrils at a time. Each tendril can be attacked (AC 20; 15 hit points; immunity to poison and psychic damage). Destroying a tendril deals no damage to the Urophion, which can extrude a replacement tendril on its next turn. A tendril can also be broken if a creature takes an action and succeeds on a DC 15 Strength check against it.

Spider Climb. The Urophion can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Multiattack. The Urophion makes four attacks with its tendrils, uses Reel, and makes one attack with its bite.

Extract Brain. Melee Weapon Attack: +7 to hit, reach 5 ft., one incapacitated humanoid grappled by the Urophion. Hit: The target takes 55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the Urophion kills the target by extracting and devouring its brain.

Tendril. Melee Weapon Attack: +7 to hit, reach 50 ft., one creature. Hit: The target is grappled (escape DC 15). Until the grapple ends, the target is restrained and has disadvantage on Strength checks and Strength saving throws, and the Urophion can't use the same tendril on another target.

Reel. The Urophion pulls each creature grappled by it up to 25 feet straight toward it.

Mind Blast (Recharge 5–6). The Urophion magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 22 (4d8 + 4) 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.