AC 16 (natural armor)
HP 127 (15d10 + 45; bloodied 63)
Speed 30 ft., swim 40 ft.
Proficiency +3; Maneuver DC 15
Damage Immunities poison
Condition Immunities frightened , poisoned
Senses darkvision 60 ft., passive Perception 13
Languages understands Deep Speech but can’t speak
Amphibious. The chuul can breathe air and water.
Detect Magic. The chuul senses a magical aura around any visible creature or object within 120 feet that bears magic.
Spell-warped. The spell-warped Chuul possesses one of the following traits.
Absorb Magic. The chuul has advantage on saving throws against spells and other magical effects. Whenever the chuul successfully saves against a spell or magical effect, it magically gains 5 (1d10) temporary hit points. While these temporary hit points last, the chuul’s pincer attacks deal an additional 3 (1d6) force damage.
King-Sized Claw. One of the chuul’s pincers deals 18 (4d6 + 4) bludgeoning damage on a successful hit. A creature grappled by this pincer makes ability checks to escape the grapple with disadvantage .
Rune Drinker. Whenever the chuul takes damage from a magic weapon, until the start of the chuul’s next turn attacks made with that weapon have disadvantage , and the chuul gains a +4 bonus to AC.
Sparking Wand. A wand of lightning bolts adorns the chuul’s carapace. A creature that starts its turn within 10 feet must make a successful DC 14 Dexterity saving throw or take 7 (2d6) lightning damage. As an action, a creature within 5 feet of the chuul can grab the wand by making a successful DC 14 Athletics or Sleight of Hand check. A creature that fails this check must make a DC 14 Dexterity saving throw. On a failed save, the creature takes 7 (2d6) lightning damage and is knocked prone . On a successful save, a creature takes half damage and isn’t knocked prone.
ACTIONS
Multiattack. If the chuul is grappling a creature, it uses its tentacle on that creature. It then makes two pincer attacks.
Pincer. Melee Weapon Attack: +7 to hit, reach 5 ft., one Large or smaller target. Hit: 11 (2d6 + 4) bludgeoning damage. If the target is a creature, it is grappled (escape DC 15). When carrying a grappled creature, the chuul can move at full speed. A pincer that is being used to grapple a creature can be used only to attack that creature.
Tentacle. A grappled creature makes a DC 14 Constitution saving throw . On a failure, it is paralyzed for 1 minute. The creature repeats the saving throw at the end of each of its turns, ending the paralysis on a success.
Combat
The chuul seeks out magical treasure. It uses its Detect Magic ability to choose the target with the most visible magic items. The chuul tries to grapple that creature and then paralyze it on the next turn. Once the chuul has at least one creature seized, it retreats, trying to carry its victim to its master.
Legends and Lore
With an Arcana or History check, characters can learn the following:
DC 15 Aboleths created chuuls as servants. Chuuls are more intelligent than they appear and can detect magic but have no desires of their own.
DC 20 A chuul’s tentacles drip a powerful paralytic toxin.
Exposure to magic transforms some chuuls into terrifying monstrosities.
1 Lured by the presence of magic, now waiting to ambush the party
2 Guarding the gates of an abandoned underwater city
3 Admiring the magic ring it wears on its tentacle
4 Leading a group of shackled humanoid captives
5 Locked in mortal combat with a giant shark
6 Oblivious to its surroundings as it receives a psychic message from its master
1 An armor-clad skeleton, its breastplate crushed by some incredible force
2 A brief distortion in the weave of magic that spellcasters in the area automatically detect
3 A shipwreck, its hull torn open like paper
4 A clutch of slimy, yellow-green egg sacs
Chuuls stalk underwater caverns or keep watch over sunken ruins.
CR 5–10 1 or 2 chuuls ; spell-warped chuul
Treasure 3 spheres enchanted with different colors of continual flame (25 gp each), spell scrolls of magic missile and sleep inscribed on bronze tablets, spellguard shield
CR 11–16 3 chuuls ; spell-warped chuul with 1d4 aboleth thralls (see aboleth)
Treasure magic chess board that plays black at novice skill level (25 gp), pearl of power , 1 trident
Aberrations are unnatural beings that don’t belong to this plane of existence. Many aberrations are telepathic and use a mental power known as psionic power instead of magic. An aboleth is an aberration.