Kassoon

Aboleth,Nihileth

Large undead, chaotic evil
Armor Class 17
Hit Points 135 (18d10 + 36)135 (18d10 + 36)
Speed 10 ft., swim 40 ft., fly 40 ft. (ethereal only, hover)
STR
21 (+5)
DEX
9 (-1)
CON
15 (+2)
INT
18 (+4)
WIS
15 (+2)
CHA
18 (+4)

Saving Throws Con +6, Int +8, Wis +6 Con +6, Int +8, Wis +6
Skills History +12, Perception +10 History +12, Perception +10
Damage Vulnerabilities
Damage Resistances acid, fire, lightning, thunder (only when
in ethereal form); bludgeoning, piercing and slashing from
nonmagical weapons
Damage Immunities cold, necrotic, poison; bludgeoning,
piercing and slashing from nonmagical weapons (only when in
ethereal form)
Condition Immunities charmed, exhaustion, frightened,
grappled, paralyzed, petrified, poisoned, prone, restrained
charmed, exhaustion, frightened,
grappled, paralyzed, petrified, poisoned, prone, restrained
Senses darkvision 120 ft., passive Perception 20darkvision 120 ft., passive Perception 20
Languages Void Speech, telepathy 120 ft.
Challenge 12 (8,400 XP)

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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.

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 weapons. In its ethereal form, it is immune to damage from nonmagical

weapons. 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.

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.
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

[b]Undead Fortitude.[/b] 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.

[b]Dual State.[/b] 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 weapons. In its ethereal form, it is immune to damage from nonmagical
weapons. 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.

[b]Void Aura.[/b] 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.
[b]Infecting Telepathy.[/b] 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

Actions

Multiattack: The nihileth makes three tentacle attacks or three
withering touches, depending on what form it is in.
Tentacle (Material Form Only): 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 (Ethereal Form Only): Melee Weapon Attack:
+8 to hit, reach 10 ft., one creature. Hit: 14 3d6+4 necrotic
damage.
Form Swap: As a bonus action, the nihileth can alter between
its material and ethereal forms at will.
Tail (Material Form Only): Melee Weapon Attack: +9 to hit,
reach 10 ft. one target. Hit: 15 3d6 + 5 bludgeoning damage.
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

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.

[b] Multiattack:[/b] The nihileth makes three tentacle attacks or three
withering touches, depending on what form it is in.
[b]Tentacle (Material Form Only):[/b] 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.
[b]Withering Touch (Ethereal Form Only):[/b] Melee Weapon Attack:
+8 to hit, reach 10 ft., one creature. Hit: 14 [3d6+4] necrotic
damage.
[b]Form Swap:[/b] As a bonus action, the nihileth can alter between
its material and ethereal forms at will.
[b]Tail (Material Form Only):[/b] Melee Weapon Attack: +9 to hit,
reach 10 ft. one target. Hit: 15 [3d6 + 5] bludgeoning damage.
[b]Enslave (3/day):[/b] 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

[b]Reactions[/b]
[b]Void Body:[/b] The nihileth can reduce the damage it takes from a
single source to 0. Radiant damage can only be reduced by half.

Legendary Actions

A nihileth 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 nihileth
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.

A nihileth’s lair
While aboleths create their lairs underwater, spending most of
their time submerged, a nihileth lair can be encountered out of
the water, often in a cave or a ruined, abandoned city.
LAIR ACTIONS
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.
A nihileth 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 nihileth
regains spent legendary actions at the start of its turn.
[b]Detect[/b]. The aboleth makes a Wisdom (Perception) check.
[b]Tail Swipe.[/b] The aboleth makes one tail attack.
[b]Psychic Drain (Costs 2 Actions).[/b] One creature charmed by
the aboleth takes 10 (3d6) psychic damage, and the aboleth
regains hit points equal to the damage the creature takes.

[b]A nihileth’s lair[/b]
While aboleths create their lairs underwater, spending most of
their time submerged, a nihileth lair can be encountered out of
the water, often in a cave or a ruined, abandoned city.
[b]LAIR ACTIONS[/b]
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.
[b]• Void absorbance.[/b] 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.
[b]REGIONAL EFFECTS[/b]
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.
 

Details

Eons ago, a group of aboleth left the Material Plane to wander
through distant planes—seeing them through magical scrying was
not enough, so these aboleth used astral magic and bodily travel to
see far beyond normal realms.
A Forgotten Tribe. As ages passed, memories of those who
departed slowly faded from the minds of those aboleth who
remained behind. Those few aboleth who did remember that
long ago some of their kin had gone plane-wandering assumed
that the wanderers must have died in distant hells or paradises.
Changed by Planar Wandering. The plane-wanderers
hadn’t died. Instead, their eons-long exposure to alien
realms and to the space between changed them, restructuring
their life force and making them into something even more
nightmarish—but better able to withstand both strange hells
and golden realms of eldritch delight.
Servants of the Void. They returned even more corrupt
and powerful than they had left, and these wandering nihileths
returned to the mortal world intent on spreading the influence
of the Void and the utter evil they found in the vast darkness
between worlds.
Undead Nature. A nihileth does not require air, food, drink,
or sleep.
Eons ago, a group of aboleth left the Material Plane to wander
through distant planes—seeing them through magical scrying was
not enough, so these aboleth used astral magic and bodily travel to
see far beyond normal realms.
A Forgotten Tribe. As ages passed, memories of those who
departed slowly faded from the minds of those aboleth who
remained behind. Those few aboleth who did remember that
long ago some of their kin had gone plane-wandering assumed
that the wanderers must have died in distant hells or paradises.
Changed by Planar Wandering. The plane-wanderers
hadn’t died. Instead, their eons-long exposure to alien
realms and to the space between changed them, restructuring
their life force and making them into something even more
nightmarish—but better able to withstand both strange hells
and golden realms of eldritch delight.
Servants of the Void. They returned even more corrupt
and powerful than they had left, and these wandering nihileths
returned to the mortal world intent on spreading the influence
of the Void and the utter evil they found in the vast darkness
between worlds.
Undead Nature. A nihileth does not require air, food, drink,
or sleep.
 
Source Tome of Beasts, p.8
 
Environments Aquatic, Coast
 
Tactics
 
Roles | | | | | | | | | |

 

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Monster Statistics by Challenge Rating

CRProf. BonusACHPAttack BonusDamage / RoundSave DC
0+2<131-6<+30-1<13
1/8+2137-35+32-313
l/4+21336-49+34-513
1/2+21350-70+36-813
1+21371-85+39-1413
2+21386-100+315-2013
3+213101-115+421-2613
4+214116-130+527-3214
5+315131-145+633-3815
6+315146-160+639-4415
7+315161-175+645-5015
8+316176-190+751-5616
9+416191-205+757-6216
10+417206-220+763-6816
11+417221-235+869-7417
12+417236-250+875-8017
13+518251-265+881-8618
14+518266-280+887-9218
15+518281-295+893-9818
16+518296-310+999-10418
17+619311-325+10105-11019
18+619326-340+10lll-11619
19+619341-355+10117-12219
20+619356-400+10123-14019
21+719401-445+11141-15820
22+719446-490+11159-17620
23+719491-535+11177-19420
24+719536-580+12195-21221
25+819581-625+12213-23021
26+819626-670+12231-24821
27+819671-715+13249-26622
28+819716-760+13267-28422
29+919761-805+13285-30222
30+919806-850+14303-32023

Damage Severity by Level

LevelSetbackDangerousDeadly
1-41d102d104d10
5-102d104d1010d10
11-164d1010d1018d10
17-2010d1018d1024d10

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