Soul Lance. Any creature, that starts its turn within 15 feet of Zamuth must succeed on a DC 21 Intelligence saving throw or be Stunned until the start of the creature’s next turn.

Legendary Resistance (3/Day). If Zamuth fails a saving throw, it can choose to succeed instead.

Magic Resistance. Zamuth has advantage on saving throws against spells and other magical effects.

Magic Weapons. Zamuth’s weapon attacks are magical.

Regeneration. Zamuth regains 20 hit points at the start of its turn. If it takes radiant damage, this trait doesn’t function at the start of its next turn. Zamuth dies only if it starts its turn with 0 hit points and doesn’t regenerate.

Multiattack. Zamuth makes three acid lash attacks.

Force Lash. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 21 (4d6 + 7) force damage. 

Lamenting Wale (Recharge 5–6). Zamuth releases a guttural howl, targeting all creatures that can hear it within 40 feet of it. The target must make a DC 21 Con saving throw. On a failure, the target takes 30 (6d10) Force damage. Unless the target succeeds the save they are knocked prone and are deaf for 1 minute. 

Juiblex can take 3 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. Juiblex regains spent legendary actions at the start of its turn.

Zamuths blast. Zamuth casts Eldritch Blast.

Attack. Zamuth makes one force lash attack.

Corrupting Touch (Costs 2 Actions). Melee Weapon Attack: +14 to hit, reach 10 ft., one creature. Hit: 14 (3d6 + 5) Force Damage. When struck the creature must make a DC 16 Charisma Save. On a failed save the creature is charmed for 1 Minute or until the effect is ended. The creature acts as if under the Charm Person spell and the effect can only be ended the same as the spell.