Aboleth

Four long tentacles writhe from this three-eyed fish-like creature’s flanks, and its green body glistens with thick, clear slime.

Large aberration, lawful evil

Armor Class 17 (natural armor)
Hit Points 135 (18d10 + 36)
Speed 10 ft., swim 40 ft.

Saving Throws Con +6, Int +8, Wis +6
Skills History +12, Perception +10
Senses darkvision 120 ft., passive Perception 20
Languages Deep Speech, telepathy 120 ft.
Challenge 10 (5,900 XP)

Special Traits

• Amphibious: It 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 5 feet 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 aboleth learns the creature’s greatest desires if the aboleth can see the creature.

Actions

• Multiattack: It makes three tentacle attacks.
• Tentacle: Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage. 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 to hit, reach 10 ft. one target. Hit: 15 (3d6 + 5) bludgeoning damage.
• Enslave (3/Day): The aboleth targets one creature it can see within 30 feet of it. The target must succeed on a DC 14 Wisdom 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 mile away from the aboleth.

Legendary Actions

The aboleth 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 creature’s turn. The aboleth regains spent legendary actions at the start of its turn.

• Detect: The aboleth makes a Wisdom (Perception) check.
• Tail Swipe: The aboleth makes one tail attack.
• Psychic Drain (Costs 2 Actions): One creature charmed by the aboleth takes 10 (3d6) psychic damage, and the aboleth regains hit points equal to the damage the creature takes.

Combat

It attacks by flailing with its long, slimy tentacles, though it prefers to fight from a distance using its illusion powers.

Enslave (Su): Three times per day, an aboleth can attempt to enslave any one living creature within 30 feet. The target must succeed on a DC 17 Will save or be affected as though by a dominate person spell (caster level 16th). An enslaved creature obeys it’s telepathic commands until freed by remove curse, and can attempt a new Will save every 24 hours to break free. The control is also broken if the aboleth dies or travels more than 1 mile from its slave. The save DC is Charisma-based.

Psionics (Sp): At will-hypnotic pattern (DC 15), illusory wall (DC 17), mirage arcana (DC 18), persistent image (DC 18), programmed image (DC 19), project image (DC 20), veil (DC 19). Effective caster level 16th. The save DCs are Charisma-based.

Slime (Ex): A blow from an it’s tentacle can cause a terrible affliction. A creature hit by a tentacle must succeed on a DC 19 Fortitude save or begin to transform over the next 1d4+1 minutes, the skin gradually becoming a clear, slimy membrane. An afflicted creature must remain moistened with cool, fresh water or take 1d12 points of damage every 10 minutes. The slime reduces the creature’s natural armor bonus by 1 (but never to less than 0). The save DC is Constitution-based.

A remove disease spell cast before the transformation is complete will restore an afflicted creature to normal. Afterward, however, only a heal or mass heal spell can reverse the affliction.

Mucus Cloud (Ex): An aboleth underwater surrounds itself with a viscous cloud of mucus roughly 1 foot thick. Any creature coming into contact with and inhaling this substance must succeed on a DC 19 Fortitude save or lose the ability to breathe air for the next 3 hours. An affected creature suffocates in 2d6 minutes if removed from the water. Renewed contact with the mucus cloud and failing another Fortitude save continues the effect for another 3 hours. The save DC is Constitution-based.

Skills: It has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.

Aboleth Mage

Combat

The save DC for the aboleth mage’s transformation tentacle attack (DC 21) and its mucus cloud (DC 21) are adjusted for its higher Constitution score. The save DC for its enslave ability (DC 16) is adjusted for its lower Charisma score, as are the save DCs for its psionic abilities: hypnotic pattern (DC 14), illusory wall (DC 16), mirage arcana (DC 17), persistent image (DC 17), programmed image (DC 18), project image (DC 19), veil (DC 18). Effective caster level 16th.

The aboleth mage uses a number of spells, such as displacement, greater invisibility, and Wall
of Force, to protect itself while seizing control of its foes with spells and innate abilities.

Typical Wizard Spells Prepared (4/6/5/4/4/3; save DC 15 + spell level)

• 0- daze, detect magic (2), resistance;
• 1st-alarm, charm person, color spray, mage armor, magic missile (2);
• 2nd-blur, bull’s strength, darkness, fox’s cunning, see invisibilty;
• 3rd-dispel magic, displacement, fly, lightning bolt;
• 4th-greater invisibility, phantasmal killer, scrying, stoneskin;
• 5th-hold monster, empowered lightning bolt, wall of force