Chaos Dreadnought

Gargantuan aberration, chaotic neutral

Armor Class 22 (natural armor)

Hit Points 462 (25d20 + 200)

Speed 30 ft., climb 30 ft.

Abilities Str 29 (+9), Dex 11 (+0), Con 27 (+8), Int 10 (+0), Wis 9 (-1), Cha 10 (+0)

Saving Throws Str +17, Dex +8, Con +16, Cha +8

Skills Athletics +17, Perception +7

Condition Immunities prone

Senses passive Perception 17

Languages –

Challenge 25 (75,000 XP)

Corporeal Instability. Any creature that touches the dreadnought, is hit by the dreadnought’s claw attack, or takes damage from being engulfed by it must succeed on a DC 24 Charisma saving throw or become a spongy, amorphous mass. The affected creature is unable to hold or use any item. Clothing, armor, and equipment become useless. The creature’s speed is reduced by 10 feet. Searing pain courses along the nerves, so strong that the creature cannot act coherently; it cannot cast spells or use magic items, and it attacks blindly, unable to distinguish friend from foe. At the start of the creature’s turn, roll 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.

Each round that the creature spends in an amorphous state, its Wisdom is reduced by 1. The target becomes a chaos beast if this reduces its Wisdom to 0.

A creature can repeat its saving throw at the end of each of its turns, ending the effect on itself with a success. A greater restoration spell or similar magic removes the affliction. And a separate greater restoration spell is required to restore any lost Wisdom.

Avoidance. If the dreadnought is subjected to an effect that allows it to make a saving throw to take only half damage, it instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Immutable Form. The dreadnought is immune to any spell or effect that would alter its form.

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

Magic Resistance. The dreadnought has advantage against spells and other magical effects.

Actions

Multiattack. The dreadnought makes three claw attacks.

Claw. Melee Weapon Attack: +17 to hit, reach 30 ft., one target. Hit: 27 (4d8 + 9) slashing damage.

Engulf. The dreadnought moves up to its speed. While doing so, it can enter a Huge or smaller creatures’ spaces. Whenever the dreadnought enters a creature’s space, the creature must make a DC 24 Dexterity saving throw.

On a successful save, the creature can choose to be pushed 5 feet back or to the side of the dreadnought. A creature that chooses not to be pushed suffers the consequences of a failed saving throw.

On a failed save, the dreadnought enters the creature’s space and the creature takes 45 (8d8 + 9) piercing damage and is engulfed. The engulfed creature can’t breathe, is restrained, and takes 45 (8d8 + 9) piercing damage at the start of each of the dreadnought’s turns. When the dreadnought moves, the engulfed creature moves with it.