Gibbering. The Zygote "Communities" babble incoherently while it can see any creature and isn't incapacitated. Each creature that starts its turn within 20 feet of the mouther and can hear the gibbering must succeed on a DC 16 Wisdom saving throw. On a failure, the creature can't take reactions until the start of its next turn and rolls a d8 to determine what it does during its turn. On a 1 to 4, the creature does nothing. On a 5 or 6, the creature takes no action or bonus action and uses all its movement to move in a randomly determined direction. On a 7 or 8, the creature makes a melee attack against a randomly determined creature within its reach or does nothing if it can't make such an attack.

Aberrant Ground. The ground in a 10-foot radius around the zygote is flesh-like difficult terrain. Each creature that starts its turn in that area must succeed on a DC 18 Strength saving throw or have its speed reduced to 0 until the start of its next turn.

Multiattack. The Zygote makes two slam attacks. If both attacks hit a Medium or smaller target, the target is grappled (escape DC 18), 

Slam. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 17 [2d10 + 5) bludgeoning damage.

Engulf. The zygote engulfs a Medium or smaller creature grappled by it. The engulfed target is restrained, and unable to breathe, and it must succeed on a DC 14 Constitution saving throw at the start of each of the Zygote's turns or take 14 (2d8 + 5); bludgeoning damage. If the zygote moves, the engulfed target moves with it. The zygote can have only one creature engulfed at a time. If a creature is dropped to 0 while engulfed, it is assimilated into the zygote. The assimilated creature is aware of its surroundings and will die if extracted.

Horrific Whispers: As an action, the Zygote can let out a cacophony of haunting whispers. Hostile creatures within 30 feet of the creature that can hear it must succeed on a DC 15 Wisdom saving throw or become frightened of until the end of its next turn.

The Zygote can take 2 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The Zygote regains spent legendary actions at the start of its turn. On initiative count 20 the zygote activates one of its Legendary actions.

Slam. The Zygote can make one slam attack

Dreadful . One creature Frightened by the Zygote movement speed drops to 0 until the end of that creatures turn.