Centuries ago, an aboleth was taken over by the larva of a mind flayer, creating a highly intelligent hybrid that soon grew as powerful as an elder brain. The abolithid seized control of the illithid colony at Black Lake and spread tentacles of influence throughout the Underdark.
Master of Black Lake. The abolithid dwells in the deepest underwater cavern of Black Lake while its enslaved minions patrol the dark water and barren shores. On an island at the center of the lake, the abolithid’s mind flayer underlings occupy the temple of a forgotten elder god, gathering captives to build an army for their master.
Huge aberration, lawful evil
Armor Class 17 (natural armor)
Hit Points 185 (17d12 + 75)
Speed 10 ft., swim 40 ft.
|21 (+5)||9 (-1)||15 (+2)||20 (+5)||16 (+3)||18 (+4)|
Saving Throws CON +6, INT +8, WIS +6
Skills Arcana +10, History +12, Perception +11
Senses Darkvision 120 ft., Passive Perception 20
Languages Deep Speech, telepathy 120 ft.
Challenge 14 (11,500 XP)
Proficiency Bonus +5
Amphibious. The abolithid can breathe air and water.
Magic Resistance. The abolithid has advantage on saving throws against spells and other magical effects.
Mucous Cloud. While underwater, the abolithid is surrounded by transformative mucus. A creature that touches the abolithid or that hits it with a melee attack while within 5 ft. of it must make a DC 14 Constitution saving throw. On a failure, the creature is diseased for 1d4 hours. The diseased creature can breathe only underwater.
Probing Telepathy. If a creature communicates telepathically with the aboleth, the abolithid learns the creature’s greatest fear if the abolithid can see the creature.
Multiattack. The abolithid makes three tentacle attacks.
Tentacle. Melee Weapon Attack:+9, Reach 10 ft., one target
Hit: 14 (2d8 + 5) bludgeoning damage plus 5 (1d10) psychic damage
If the target is Medium or smaller, it is grappled, escape DC 15, and must succeed on a DC 15 Intelligence saving throw or be stunned until this grapple ends.
If the target is a creature, it must succeed on a DC 14 Constitution saving throw or become diseased. The disease has no effect for 1 minute and can be removed by any magic that cures disease. After 1 minute, the diseased creature’s skin becomes translucent and slimy, the creature can’t regain hit points unless it is underwater, and the disease can be removed only by heal or another disease-curing spell of 6th level or higher. When the creature is outside a body of water, it takes 6, 1d12, acid damage every 10 minutes unless moisture is applied to the skin before 10 minutes have passed.
Tail. Melee Weapon Attack:+9, Reach 10 ft., one target
Hit: 15 (3d6 + 5) bludgeoning damage
Mind Blast (Recharge 5–6). The abolithid magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 22 (4d8 + 4) psychic damage and be stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Enslave (3/day). The abolithid targets one creature it can see within 30 ft. of it. The target must succeed on a DC 14 Wisdom saving throw or be magically charmed by the abolithid until the abolithid dies or until it is on a different plane of existence from the target. The charmed target is under the abolithid’s control and can’t take reactions, and the abolithid and the target can communicate telepathically with each other over any distance. Whenever the charmed target takes damage, the target can repeat the saving throw. On a success, the effect ends. No more than once every 24 hours, the target can also repeat the saving throw when it is at least 1 mile away from the abolithid.
Extract Brain. Melee Weapon Attack:+8, Reach 10 ft., one incapacitated humanoid grappled by the abolithid
Hit: 55 (10d10) piercing damage
This attack can only be used on a incapacitated humanoid grappled by the abolithid. If this damage reduces the target to 0 hit points, the abolithid kills the target by extracting and devouring its brain.
Innate Spellcasting (Psionics). The abolithid’s innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:
• At will: detect thoughts, levitate
• 1/day each: dominate monster, plane shift (self only)
The abolithid can take 3 legendary actions, choosing from the options below. Only one legendary option can be used at a time and only at the end of another creature’s turn. The abolithid regains spent legendary actions at the start of its turn.
Detect. The abolithid makes a Wisdom (Perception) check to detect hidden or invisible creatures.
Tail Swipe. The abolithid makes one tail attack.
Psychic Drain (Costs 2 Actions). One creature charmed by the abolithid takes 10 (3d6) psychic damage, and the aboleth regains hit points equal to the damage the creature takes.
The abolithid’s lair is the crumbling ruins of an ancient aboleth fortress beneath Black Lake. It emerges from the depths periodically to accept sacrifices and new slaves.
On initiative count 20 (losing initiative ties), the abolithid can take one of the following lair actions; the abolithid can’t take the same lair action two rounds in a row:
Force Wall. The elder brain casts wall of force.
Psychic Storm. Water in the abolithid’s lair magically becomes a conduit for the creature’s rage. The abolithid can target any number of creatures it can see in such water within 90 feet of it. A target must succeed on a DC 14 Wisdom saving throw or take 7 (2d6) psychic damage. The abolithid can’t use this lair action again until it has used a different one.
Psychic Inspiration. The abolithid targets one friendly creature it can sense within 120 feet of it. The target has a flash of inspiration and gains advantage on one attack roll, ability check, or saving throw it makes before the end of its next turn.
The territory around Black Lake is corrupted by the abolithid’s psionic presence, which creates one or more of the following effects:
Slimy Stone. Underground surfaces within 1 mile of the abolithid’s lair are slimy and wet and are difficult terrain.
Sick Water. Water sources within 1 mile of the lair are supernaturally fouled. Enemies of the abolithid that drink such water vomit it within minutes.
Telepathic Eavesdropping. The abolithid can overhear any telepathic conversation within 5 miles of it. The creature that initiated the telepathic conversation makes a DC 18 Wisdom saving throw when telepathic contact is first established. If the save is successful, the creature is aware that something is eavesdropping. The nature of the eavesdropper isn’t revealed.
If the abolithid dies, the first two effects fade over the course of 3d10 days.
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