- 10 (5,900 XP)
Amphibious. The aboleth can breathe air and water.
Mucous Cloud. While underwater, the aboleth is surrounded by transformative mucus. A creature that touches the aboleth or that hits it with a melee attack while within 1.5 meters of it must make a DC 14 Fortitude 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 aboleth learns the creature’s greatest desires if the aboleth can see the creature.
Spellcasting. The aboleth is a 13th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 16, +8 to hit with spell attacks). It has 10 mana, a mana limit of 2, regains all expended mana when it finishes a long rest and regains half its total mana when it finishes a short rest, and knows the following spells:
1 mana: agonizing rebuke, call to mind, confusion, disable, ego whip, haze senses, meld mindcrystal, mind over body, mind spike, mind trap, psychic fortress, sending, sense minds, thought shield, wandering mind
2 mana: aphasia, co-opt concentration, detect thoughts, hold creature, mind blast, mind control, modify memory, personality parasite, psychic crush, psychic reformation, synaptic static, telepathic bond
Multiattack. The aboleth makes three tentacle attacks.
Tentacle. Melee Weapon Attack: +9 to hit, reach 3 m. Hit: 12 (2d6 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Fortitude 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 health unless it is underwater, and the disease can be removed only by a disease-curing spell cast at 3 or more mana. 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 to hit, reach 3 m. Hit: 15 (3d6 + 5) bludgeoning damage.
Enslave (3/Day). The aboleth targets one creature it can see within 9 meters of it. The target must succeed on a DC 14 Will saving throw or be magically charmed by the aboleth until the aboleth dies or until it is on a different plane of existence from the target. The charmed target is under the aboleth’s control and can’t take reactions, and the aboleth 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 1.6 kilometers away from the aboleth.
The aboleth 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 aboleth regains spent legendary actions at the start of its turn.
Detect. The aboleth makes a Perception check.
Psychic Drain (Costs 2 Actions). One creature charmed by the aboleth takes 10 (3d6) psychic damage, and the aboleth regains health equal to the damage the creature takes.
Tail Swipe. The aboleth makes one tail attack.