Beast of Bacchanalia Bay

Water Pocket: While the creature isn't incapicated, a 5-foot radius around the beast is a magically suspended bubble of brackish water that it moves telekinetically.  Each creature that starts its turn in that area must succeed on a DC 10 Strength saving throw or have its speed reduced to 0 until the start of its next turn and have disadvantage on all melee attacks made within the bubble.

Aura of Aberrant Insanity: The Beast psychically babbles incoherently while it can see any creature and isn't incapacitated. Each creature that starts its turn within 20 feet of the beast rolls high/low. If they roll low, they must succeed on a DC 14 Wisdom saving throw. On a failure, the creature takes 8 (3d4) psychic damage, can't take reactions until the start of its next turn, and rolls a d8 to determine what it does during its next 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. If a creature fails its save against this effect 3 times they roll on the Short Term Madness table and suffer this effect for 1d6 rounds rather than 1d10 minutes. If they fail their save 5 times, they must roll on the Indefinite Madness Table.

Multiattack. The Beast may make a Bite attack for each remaining head, any of them can be replaced with Fling, or it may instead choose to use its Lightning Storm attack.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d6 + 5) piercing damage and causes a contested grapple check with the beast. Until this grapple ends, the target is restrained. If the target is killed while grappled, it is absorbed into the beast over the course of 3 rounds. Each head may grapple a different creature.

Fling. One Medium or smaller object held or creature grappled by one of the beast's maws is thrown up to 60 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 14 Dexterity saving throw or take the same damage and be knocked prone.

Lightning Storm. The beast creates three bolts of lightning, each of which can strike a target the beast can see within 90 feet of it. A target must make a DC 14 Dexterity saving throw, taking 11 (2d10) lightning damage on a failed save, or half as much damage on a successful one.

Reactive Spittle (Recharge 4–6). The beast spits a chemical glob at a point it can see within 30 feet of it. The glob explodes in a blinding flash of light on impact and sprays acidic goo. Each creature within 15 feet of the flash must succeed on a DC 14 Con saving throw or be blinded until the end of the beast's next turn. Each creature within range must also then make a DC 14 Dexterity saving throw, taking 21 (6d6) Acid Damage on a failed save, or half as much damage on a successful one.