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Aboleth, Nihilith

Large · Undead · CR 12 · Chaotic Evil

Source. Tome of Beasts

17 (natural armor)

135 (18d10+36)

Ability Scores

Core attributes and their modifiers.

STR

DEX

-1

CON

INT

WIS

CHA

Overview

Category Monsters

Size Large

Type Undead

Alignment Chaotic Evil

XP 8400

Initiative Bonus -1

Movement

Walk 10 ft (3 m)

Fly 50 ft (15.2 m)

Swim 40 ft (12.2 m)

Climb 5 ft (1.5 m)

Crawl 5 ft (1.5 m)

Hover Yes

Senses

Darkvision 120 ft (36.6 m)

Passive Perception 20

Saving Throws

Constitution +6 Intelligence +8 Wisdom +6

Skills

History +12 Perception +10

Languages

Void Speech, telepathy 120.0 ft (36.6 m).

Resistances & Immunities

Damage Immunities

cold, necrotic, poison; bludgeoning, piercing and slashing from nonmagical attacks (only when in ethereal form)

Damage Resistances

acid, fire, lightning, thunder (only when in ethereal form); bludgeoning, piercing and slashing from nonmagical attacks

Condition Immunities

charmed, exhaustion, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained

Traits

Dual State

A nihileth exists upon the Material Plane in one of two forms and can switch between them at will. In its material form, it has resistance to damage from nonmagical attacks. In its ethereal form, it is immune to damage from nonmagical attacks. The creature's ethereal form appears as a dark purple outline of its material form, with a blackish-purple haze within. A nihileth in ethereal form can move through air as though it were water, with a fly speed of 40 feet.

Infecting Telepathy

If a creature communicates telepathically with the nihileth, or uses a psychic attack against it, the nihileth can spread its disease to the creature. The creature must succeed on a DC 14 Wisdom save or become infected with the same disease caused by the nihileth's tentacle attack.

Nihileth's Lair

on initiative count 20 (losing initiative ties), the nihileth can take a lair action to create one of the magical effects as per an aboleth, or the void absorbance action listed below. The nihileth cannot use the same effect two rounds in a row.

Void Absorbance: A nihileth can pull the life force from those it has converted to nihilethic zombies to replenish its own life. This takes 18 (6d6) hit points from zombies within 30 feet of the nihileth, spread evenly between the zombies, and healing the nihileth. If a zombie reaches 0 hit points from this action, it perishes with no Undead Fortitude saving throw.

Regional Effects

the regional effects of a nihileth's lair are the same as that of an aboleth, except as following.

Water sources within 1 mile of a nihileth's lair are not only supernaturally fouled but can spread the disease of the nihileth. A creature who drinks from such water must make a successful DC 14 Constitution check or become infected.

Undead Fortitude

If damage reduces the nihileth to 0 hit points, it must make a Constitution saving throw with a DC of 5 + the damage taken, unless the damage is radiant or from a critical hit. On a success, the nihileth drops to 1 hit point instead.

Void Aura

The undead nihileth is surrounded by a chilling cloud. A living creature that starts its turn within 5 feet of a nihileth must make a successful DC 14 Constitution saving throw or be slowed until the start of its next turn. In addition, any creature that has been diseased by a nihileth or a nihilethic zombie takes 7 (2d6) cold damage every time it starts its turn within the aura.

Actions

Enslave

3/day

The nihileth 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 nihileth until the nihileth dies or until it is on a different plane of existence from the target. The charmed target is under the nihileth's control and can't take reactions, and the nihileth 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 nihileth.

Form Swap

As a bonus action, the nihileth can alter between its material and ethereal forms at will.

Multiattack

The nihileth makes three tentacle attacks or three withering touches, depending on what form it is in.

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.

Tail

+9 to hit, reach 10 ft (3 m). Hit: 3d6 bludgeoning damage.

Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 15 (3d6 + 5) bludgeoning damage.

Tentacle

+9 to hit, reach 10 ft (3 m). Hit: 2d6 damage.

Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage. If the target creature is hit, it must make a successful DC 14 Constitution saving throw or become diseased. The disease has no effect for 1 minute; during that time, it can be removed by lesser restoration or comparable magic. After 1 minute, the diseased creature's skin becomes translucent and slimy. The creature cannot regain hit points unless it is entirely underwater, and the disease can only be removed by heal or comparable magic. Unless the creature is fully submerged or frequently doused with water, it takes 6 (1d12) acid damage every 10 minutes. If a creature dies while diseased, it rises in 1d6 rounds as a nihilethic zombie. This zombie is permanently dominated by the nihileth.

Withering Touch

+8 to hit, reach 10 ft (3 m). Hit: 3d6 necrotic damage.

Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: 14 (3d6 + 4) necrotic damage.

Reactions

Void Body

The nihileth can reduce the damage it takes from a single source to 0. Radiant damage can only be reduced by half.

Legendary Actions

Detect

Cost 1

The aboleth makes a Wisdom (Perception) check.

Psychic Drain

Cost 2

One creature charmed by the aboleth takes 10 (3d6) psychic damage, and the aboleth regains hit points equal to the damage the creature takes.

Tail Swipe

Cost 1

The aboleth makes one tail attack.

About Aboleth, Nihilith

Aboleth, Nihilith is a large undead with a Challenge Rating of 12. It has a chaotic evil alignment.

In combat, this creature maintains an Armor Class of 17 and possesses 135 hit points (derived from 18d10+36).

Aboleth, Nihilith has communication capabilities including Void Speech, telepathy 120 ft.. This allows it to interact verbally with various creatures and characters.

GM Tips: Using Aboleth, Nihilith

3 tips available

When using Aboleth, Nihilith in your D&D 5e campaign, consider these tactical approaches:

Flight Control Strategy: Target flying creatures with spells like 'Hold Person', 'Web', or 'Grease' to ground them. Without flight restriction, they can escape melee range easily. Consider area denial spells below their flight altitude to force them into disadvantageous positions.
Aquatic Combat: This creature can swim at 40 ft. It has advantage in water environments. Consider fighting on land or using water-based spells against it.
Telepathic Communication: This creature can communicate telepathically, making it excellent for coordination with allies. Silence spells won't stop its communication. Consider 'Mind Blank' or abilities that block telepathy.

Player Guide: Facing Aboleth, Nihilith

3 strategies available

When your party encounters this creature, keep these strategies in mind:

Counter Flight Advantage: This creature can fly! Use ranged attacks, reach weapons, or spells like 'Thunderwave' to push it away. Consider 'Gust of Wind' or 'Earthbind' to ground it. Melee characters need fly speed or flight magic to engage.
Aquatic Combat Defense: This creature can swim at 40 ft! It has advantage in water. Fight on land if possible. Use 'Control Water' or drain water sources to limit its mobility.
Telepathy Awareness: This creature communicates telepathically! It can coordinate with allies silently. Silence won't stop it. Use 'Mind Blank' or abilities that block telepathy. Be cautious of mental attacks.

Encounter Building Calculator

Standard Party Encounter (4-5 characters):

This creature is a medium encounter for a party of 4 characters of level 12.

Solo Encounter:

A single character of level 16 (up to level 20) can face this creature in a medium to hard encounter.

Experience Point Thresholds:

Medium: 15,600 XP
Hard: 23,400 XP
Deadly: 31,200 XP

Based on D&D 5e Dungeon Master's Guide encounter building guidelines. CR roughly equals party level for medium encounters.

Frequently Asked Questions

What is the challenge rating of Aboleth, Nihilith?: Aboleth, Nihilith has a Challenge Rating of 12, making it appropriate for parties of level 12.0.
What type of creature is Aboleth, Nihilith?: Aboleth, Nihilith is a Large Undead, which affects how certain spells and abilities interact with it.
What languages does Aboleth, Nihilith speak?: Aboleth, Nihilith can communicate in Void Speech, telepathy 120 ft..