Amphibious. The genetic horror can breathe air and water.
Grasping Tendrils. The genetic horror can have up to three tendrils at a time. Each tendril can be attacked (AC 20; 10 hit points; immunity to poison and psychic damage). Destroying a tendril deals no damage to the horror, 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.
Rejuvination. If it dies, the genetic horror has a 25% chance to return to life at half health in 24 hours.
Spider Climb. The genetic horror can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Sure-Footed. The genetic horror has advantage on Strength and Dexterity Saving Throws made against Effects that would knock it prone.
Multiattack. The horror makes one attacks with one of its tendrils, uses Reel, and makes one Attack with its claw.
Claw. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage.
Spit Poison: Ranged Weapon Attack: +4 to hit, range 15/30 ft., one creature. Hit: The target must make a DC 12 Constitution saving throw, taking 15 (3d8) poison damage on a failed save, or half as much damage on a successful one.
Reel. The horrorr pulls each creature Grappled by it up to 25 ft. straight toward it.
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 horror can't use the same tendril on another target. Targets that are restrained take 1d6 piercing damage at the beginning of each turn.