Another thematically tweaked demon lord for Out of the Abyss.
Huge fiend (demon) chaotic evil
Armour Class 18 (natural armour)
Hit Points 350 (28d12 + 168)
Speed 30 ft.
STR 29 (+9) DEX 14 (+2) CON 26 (+8)
INT 20 (+5) WIS 17 (+3) CHA 25 (+7)
Saving Throws Dex +7, Con +13, Wis +12
Skills Perception +12
Damage Resistances cold, fire, lightning.
Damage Immunities poison; bludgeoning, piercing, and slashing that is nonmagical.
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, grapples, paralysed, petrified, poisoned, prone, restrained, stunned and unconscious.
Senses Truesight 120 ft., passive Perception 22
Languages all, telepathy 120 ft.
Challenge 23 (50,000 XP)
Amorphous. Juiblex can move through a space as narrow as 1 inch wide without squeezing.
Foul. Any creature, other than an ooze, that starts its turn within 10 feed of Juiblex must succeed on a DC 21 Constitution saving throw or be poisoned until the start of the creature‘s next turn.
Legendary Resistance (3/Day). If Demogorgon fails a saving throw, he can choose to succeed instead.
Magic Resistance. Demogorgon has advantage on saving throws against spells and other magical effects.
Magic Weapons. Demogorgon’s weapon attacks are magical.
Regeneration. Juiblex regains 20 hit points at the start of its turn. If it takes fire or radiant damage, this trait doesn’t function at the start of the Juiblex’s next turn. Juiblex’s body is destroyed only if it starts its turn with 0 hit points and doesn’t regenerate.
Spider Climb. Juiblex can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.
Multiattack. Juiblex makes three acid lash attacks.
Acid Lash. Melee Weapon Attack: +14 to hit, reach 10ft., one target.
Hit: 21 (4d6 + 7) acid damage. Any creature killed by this attack is drawn into Juibelx’s body, and the corpse is obliterated after 1 minute.
Heaving Mass. As part of its move action, Juiblex moves up to its speed. While doing so, it can enter Huge or smaller creatures’ spaces. Whenever Juiblex enters a creature’s space, the creature must make a DC 21 Dexterity saving throw. On a successful save, the creature can choose to be pushed 5 feet back or to the side of Juiblex. A creature that chooses not to be pushed suffers the consequences of a failed saving throw. On a failed save, Juiblex enters the creature’s space, and the creature takes 10 (3d6) acid damage and is engulfed. The engulfed creature can’t breathe, is restrained, and takes 21 (6d6) acid damage at the start of each of the Juiblex’s turns. When Juiblex, the engulfed creature moves with it. An engulfed creature can try to escape by taking an action to make a DC 21 Strength check. On a success, the creature escapes and enters a space of its choice within 5 feet of Juiblex.
Eject Slime (Recharge 5-6). Juiblex spews out a corrosive slime targeting one creature that it can see within 60 feet of it. The target must make a DC21 Dexterity saving throw. On a failure, the target takes 55 (10d10) acid damage. Unless the target avoids taking any of this damage, any metal armour worn by the target takes a permanent -1 penalty to the AC it offers, and any metal weapon it is carrying or wearing takes a permanent -1 penalty to damage rolls. The penalty worsens each time a target is subject to this effect. If the penalty on an object drops to -5, the object is destroyed.
Ooze Scion. The first time Juiblex is bloodied (reduced to 50% of its original hit points) it ejects six black puddings. These creatures act on Juiblex’s turn but immediately after it.
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 creatures turn. Juiblex regains spent legendary actions at the start of his turn.
Burning Excretion. Juiblex casts acid splash at maximum caster level.
Shuddering Rebuke. Juiblex makes one acid lash attack.
Corrupting Touch (Costs 2 Actions). Melee Weapon Attack: +14 to hit, reach 10ft., one creature. Hit: 21 (4d6 + 7) poison damage, and the target is slimed. Until the slime is scraped off with an action, the target is poisoned, and any creature, other than an ooze, is poisoned while within 10 feet of the target.