b'Nihileth \n'b'  Large   undead ,  chaotic evil  \n'b'  Armor Class  17 (natural armor)  Hit Points  157 (21d10 + 42)  Speed  10 ft., swim 40 ft. (fly 40 ft. (hover) in Void ghost form)\n'b' STATS STR: 21 (+5) DEX:  9 (-1)  CON:  15 (+2)  INT:  18 (+4)  WIS:  15 (+2)  CHA:  18 (+4)  \n'b'\n'b'\n'b'\n'b'\n'b'\n'b'\n'b'  Saving Throws   Con  +6,  Int  +8,  Wis  +6  Skills   History  +12,  Perception  +10  Damage Resistances  bludgeoning, piercing and slashing from nonmagical attacks  Damage Immunities  cold, necrotic, poison  Condition Immunities   charmed ,  exhaustion ,  frightened ,  grappled ,  paralyzed ,  petrified ,  poisoned ,  restrained   Senses   darkvision  120 ft., passive  Perception  20  Languages  Void Speech, telepathy 120 ft.  Challenge  13 (10,000 XP)  Proficiency Bonus  +5 \n'b' SPECIAL TRAITS \n'b'\n'b'  Ghostly Body (Void Ghost Form Only) . The nihileth has  resistance  to acid, fire, lightning, and thunder damage, it has immunity to the  prone  condition, and it has immunity to bludgeoning, piercing, and slashing damage from nonmagical attacks. In addition, the nihileth can move through other creatures and objects as if they were  difficult terrain . It takes 5 (1d10) force damage if it ends its turn inside an object. \n'b'  Infecting Telepathy . If a creature communicates telepathically with the nihileth, or deals psychic damage to it, the creature must succeed on a DC 15  Wisdom  saving throw or become infected with the nihilethic rot disease. \n'b'  Nihilethic Rot . This disease takes 1 minute to manifest in an infected creature, during which time the disease can be removed with the  lesser restoration  spell. After 1 minute, the creature\xe2\x80\x99s flesh becomes slimy and translucent, and the disease can be cured only by the  heal  spell or similar magic. Until this disease is cured, the creature can\xe2\x80\x99t regain  hp  unless it is submerged in water, and it can breathe air and water. The creature must be submerged in water at least once every 2 hours to avoid suffocating, and if it is outside a body of water, it takes 7 (2d6) acid damage every 10 minutes, unless moisture is applied to its skin before 10 minutes have passed. If a Humanoid dies while infected with this disease, it rises 1 minute later as a  nihilethic zombie  under the nihileth\xe2\x80\x99s control. If a Large giant or monstrosity dies while infected with this disease, it rises 1 minute later as a nihilethic dominator under the nihileth\xe2\x80\x99s control. \n'b'  Undead Fortitude . If damage reduces the nihileth to 0  hp , 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  hp  instead. \n'b'  Undead Nature . The nihileth doesn\xe2\x80\x99t require air, food, drink, or sleep. \n'b'  Void Aura . The nihileth is surrounded by a chilling cloud. A creature that isn\xe2\x80\x99t a construct or undead and that starts its turn within 5 feet of the nihileth must succeed on a DC 15  Constitution  saving throw or its speed is halved until the start of its next turn. In addition, a creature infected with nihilethic rot takes 7 (2d6) cold damage when it starts its turn within this aura. \n'b'\n'b' ACTIONS \n'b'\n'b'  Multiattack . The nihileth makes two Tentacle attacks and one Tail  attack , or it makes three Withering Touch attacks. \n'b'  Tail (Undead Form Only) .  Melee Weapon Attack : +10 to hit, reach 10 ft. one target.  Hit : 15 (3d6 + 5) bludgeoning damage. \n'b'  Tentacle (Undead Form Only) .  Melee Weapon Attack : +10 to hit, reach 10 ft., one target.  Hit : 12 (2d6 + 5) bludgeoning damage, and the target must succeed on a DC 15  Constitution  saving throw or contract the nihilethic rot disease (see the Nihilethic Rot trait). Withering Touch (Void Ghost Form Only).  Melee Spell Attack : +9 to hit, reach 10 ft., one creature.  Hit : 14 (3d6 + 4) necrotic damage. \n'b'\n'b' BONUS ACTIONS \n'b'\n'b'  Void Shape . The nihileth magically transforms into a dark purple, Void ghost form or back into its Undead form. Its statistics, other than its speed, resistances, and immunities, are the same in each form. Any equipment it is wearing or carrying changes with it. It reverts to its Undead form if it dies. \n'b'\n'b' REACTIONS \n'b'\n'b'  Void Body . When the nihileth takes damage, it can reduce the damage to 0. Radiant damage can be reduced by only half. \n'b'\n'b' LEGENDARY ACTIONS \n'b' The nihileth can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature\xe2\x80\x99s turn. The nihileth regains spent legendary actions at the start of its turn. \n'b'\n'b'  Detect . The nihileth makes a  Wisdom  ( Perception ) check. \n'b'  Tail Swipe . The nihileth makes one Tail  attack . \n'b'  Rotten Drain (Costs 2 Actions) . One creature infected with the nihilethic rot disease within 30 feet of the nihileth takes 10 (3d6) psychic damage, and the nihileth regains  hp  equal to that amount. \n'b'\n'b' LAIR \n'b' While aboleths create their lairs underwater, spending most of their time submerged, a nihileth can create a lair outside the water, often in a cave or a ruined, abandoned city. Nihileth lairs on land typically contain several pools of water and are often within at least 1 mile of a large body of water, as the nihileth\xe2\x80\x99s ability to fully function outside of water is limited. \n'b' On initiative count 20 (losing initiative ties), the nihileth can take a lair action to cause one of the following effects; the nihileth can\xe2\x80\x99t use the same effect two rounds in a row: \n'b'\n'b'  Open the Void . Up to three points in water the nihileth can see within 90 feet of it become conduits to the Void. Each creature within 10 feet of a point must succeed on a DC 15  Wisdom  saving throw or take 7 (2d6) necrotic damage. \n'b'  Void Absorbance . The nihileth can pull the life force from nearby  nihilethic zombies \xc2\xa0and dominators to replenish its own life. Nihilethic dominators and zombies within 30 feet of the nihileth take a total of 21 (6d6) psychic damage, divided evenly between them, and the nihileth regains  hp  equal to that amount. If a zombie or dominator is reduced to 0  hp  from this damage, it is destroyed. \n'b'  Void Shuffle . The nihileth calls on the power of the Void within its lair to rearrange its servitors. The nihileth can  teleport  each nihilethic dominator and  zombie  it can see within 60 feet of it to an unoccupied space within 15 feet of the target\xe2\x80\x99s starting location. \n'b'\n'b' REGIONAL EFFECTS \n'b' The region containing a nihileth\xe2\x80\x99s lair is corrupted by its presence, which creates one or more of the following effects: \n'b'\n'b'  Befouled Water . Water sources within 1 mile of a nihileth\xe2\x80\x99s lair are not only supernaturally fouled but can spread the nihileth\xe2\x80\x99s disease. A creature that drinks such water must succeed on a DC 11  Constitution  saving throw or become infected with the nihilethic rot disease (see the Nihilethic Rot trait). \n'b'  Thinned Veil . The veil between the Material Plane and the Void is thinner within 1 mile of the nihileth\xe2\x80\x99s lair. Beasts born or hatched in the area often have additional vestigial limbs, protoeyes, black or sludge-like blood, or similar signs of the corrupting influence of the Void. \n'b'\n'b' ABOUT \n'b' Eons ago, a group of  aboleth  left the Material Plane to wander through distant planes\xe2\x80\x94seeing them through magical  scrying  was not enough, so these  aboleth  used astral magic and bodily travel to see far beyond normal realms. \n'b'  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 died in distant hells or paradises. \n'b'  Changed by Planar Wandering . The plane-wanderers hadn\xe2\x80\x99t died. Instead, their eons-long exposure to alien realms and the space between changed them, restructuring their life force, making them into something even more nightmarish\xe2\x80\x94but better able to withstand both strange hells and golden realms of eldritch delight. They returned even more corrupt and powerful than when 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. \n'b'  Undead Servitors . Humanoids, giants, and monstrosities that succumb to the nihileth\xe2\x80\x99s disease transform into servitors for the twisted aboleths. Most humanoids transform into  nihilethic zombie , while the larger giants and monstrosities transform into nihilethic dominators. While the creatures retain much of the general shape they had in life, these servitors have translucent and slimy skin, and are adept swimmers, able to function in water or on land in service to their nihileth masters.'