#dd monster

Welp. First one. I’ll try to number them but I can already see myself losing track. Enjoy this jelly cube.

SYSTOLE

Are you looking for a monster to really fuck up your players? Well, look no further. From high damage to a nasty little surprise that’ll scar your players forever, the Systole has it all. 

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Kelvezu
Medium fiend (demon), chaotic evil
Armor Class 19 (natural armor)
Hit Points 217 (29d8 + 87)
Speed30 ft., fly 60 ft.
Str21,Dex24,Con16,Int17,Wis16,Cha16
Saving Throws Dex +13, Int +9, Wis +9
SkillsStealth +13
Damage Immunities poison
Damage Resistances cold, fire, lightning; bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunitiespoisoned
Sensestruesight 120 ft. passive Perception 13
LanguagesAbyssal, telepathy 120 ft.
Challenge18 (20000 XP)
Evasion. Whenever the kelvezu is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, the kelvezu instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.
Magic Resistance. The kelvezu has advantage on saving throws against spells and other magical effects.
Magic Weapons. The kelvezu’s weapon attacks are magical.
Sneak Attack (1/Turn). The kelvezu deals an extra 28 (8d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the kelvezu that isn’t incapacitated and the kelvezu doesn’t have disadvantage on the attack roll.
Actions
Multiattack. The kelvezu makes five attacks: three with its scimitar, and two with its dagger.
Scimitar.Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 10 (1d6+7) slashing damage and 7 (2d6) poison damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 17 Constitution saving throw or lose 4 (1d8) hit points at the start of each of its turns due to a bleeding wound. Each time the kelvezu hits the wounded target with this attack, the damage dealt by the wound increases by 4 (1d8). Any creature can take an action to stanch the wound with a successful DC 17 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.
Dagger.Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 9 (1d4+7) piercing damage and 7 (2d6) poison damage. If the target is a creature other than an undead or a construct, it must succeed on a DC 17 Constitution saving throw or lose 4 (1d8) hit points at the start of each of its turns due to a bleeding wound. Each time the kelvezu hits the wounded target with this attack, the damage dealt by the wound increases by 4 (1d8). Any creature can take an action to stanch the wound with a successful DC 17 Wisdom (Medicine) check. The wound also closes if the target receives magical healing.
Teleport.The kelvezu magically teleports, along with any equipment it is wearing or carrying, up to 120 feet to an unoccupied space it can see.

If mariliths are the generals of Abyssal armies, and balors the kings of Abyssal realms, then kelvezus are the assassins and spies of the Abyssal realms. Rather than leading other demons into battle, they serve as agents of elimination, almost always working alone. While not able to magically disguise itself, its human-like shape makes it quite easy for it to disguise itself as a human or tiefling with just a tinge of work from a disguise kit. Kelvezus are around the same height and weight as a human. 

Originally from the Monster Manual II.

Rot Reaver
Medium aberration, neutral evil
Armor Class 16 (natural armor)
Hit Points 97 (15d8 + 30)
Speed30 ft., climb 20 ft.
Str 15,Dex 14,Con 15,Int 7,Wis 12,Cha 16
Damage Resistances necrotic, poison; bludgeoning, piercing, and slashing from nonmagical attacks
Sensesdarkvision 60 ft. passive Perception 11
LanguagesCommon
Challenge 6 (2300 XP)
Drain Unlife. Whenever the rot reaver damages an undead creature with a melee weapon attack, the rot reaver regains that many hit points.
Actions
Multiattack. The rot reaver makes two attacks with its cleaver. It then may make up to two tongue attacks against any creature it has hit with a cleaver attack this turn.
Cleaver.Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 7 (1d10+2) slashing damage. A humanoid slain by this attack rises 1 hour later as a zombie under the rot reaver’s control.
Tongue.Melee Weapon Attack: +5 to hit, reach 5 ft., one creature that the rot reaver has hit with its cleaver this turn. Hit: 4 (1d4+2) piercing damage plus 10 (3d6) necrotic damage.

These wretched creatures crave the taste of undead flesh. It will consume the undead, but its malevolent nature causes to derive even greater satisfaction from killing the living, reanimating them, and then feasting on their negative energy. It is believed that they were created to serve in some long-forgotten war between mages, to counter a horde of undead. It walks like an ape, its long glistening tongues wrapped around its arms to drain victims of life. It is often accompanied by two to five zombies as well, as escorts and a source of food when the creature needs to restore its life force. When hunched, as they usually are, rot reavers around 4 feet tall; drawn up to their full height, they stand around 6 feet tall. In either case, they weigh around 250 pounds. 

Originally from the Monster Manual III

Rat King
Small monstrosity, unaligned
Armor Class14
Hit Points 112 (15d6 + 60)
Speed30 ft., climb 15 ft., swim 15 ft.
Str12,Dex19,Con18,Int5,Wis14,Cha11
Condition Immunities charmed, frightened, paralyzed, petrified
Sensesdarkvision 60 ft. passive Perception 12
Languages-
Challenge5 (1800 XP)
Keen Smell. The rat king has advantage on Wisdom (Perception) checks that rely on smell.
Speak With Rats. The rat king can communicate with normal rats (including giant rats).
Actions
Multiattack. The rat king makes five bite attacks.
Bite.Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 6 (1d4+4) piercing damage. If the target is a creature, it must succeed on a DC 14 Constitution saving throw or contract a disease. Until the disease is cured, the target can’t regain hit points except by magical means, and the target’s hit point maximum decreases by 3 (1d6) every 24 hours. If the target’s hit point maximum drops to 0 as a result of this disease, the target dies.

Sometimes, several rats, endlessly writing in the darkness and muck, end up with their tails entangled and eventually knotted together. Sometimes, when this happens, the pain and torment of their restrained existence causes the rats’ sentience to merge into one single creature. Thoroughly infested with disease, the sight of a rat king can be enough to send an entire city into panic for the illnesses it may spread. A rat king is about 3 feet tall and weighs around 15 pounds. 

Originally from the Pathfinder Bestiary 4.

Abrian
Medium monstrosity, chaotic evil
Armor Class 15 (natural armor)
Hit Points 22 (4d8 + 4)
Speed50 ft.
Str13,Dex 16,Con 12, Int 7,Wis11,Cha10
Damage Resistancesthunder
Sensesdarkvision 60 ft. passive Perception 10
LanguagesAbyssal
Challenge1 (200 XP)
Actions
Multiattack. The abrian makes two attacks: one with its beak and one with its kick.
Beak.Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6+3) piercing damage.
Kick.Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:7 (1d8+3) slashing damage.
Shriek (Recharge 5-6). The abrian lets out a horrible shriek. When it does, each creature that isn’t an abrian within 30 feet of the abrian must succeed on a DC 11 Constitution saving throw or be deafened for 1 hour. If the saving throw fails by 5 or more, the target is also stunned until the end of its next turn. A creature that succeeds on its save is immune to the Shriek of all abrians for 24 hours.

These ostrich-like birds lurk on the open plains of the Abyss, Gehenna, and other desolate regions of the outer planes. They are smarter than they look, and sometimes trade with nomads in those regions. They tend to travel in flocks of four to ten individuals, though a flock can have up to forty. In battle, they spread out and dart in and out of the fray in pairs, trying to outflank their opponents. They have black and orange feathers, and two small shrunken arms in place of wings, which are adequate for manipulating objects, but useless in combat. They stand around 6 feet tall and weigh around 250 lbs. 

Originally from the Fiend Folio. 

Plague Brush
Gargantuan plant, unaligned
Armor Class 12 (natural armor)
Hit Points 333 (18d20 + 144)
Speed60 ft.
Str27.Dex10,Con26,Int1,Wis11,Cha10
Damage Resistancespiercing
Damage Vulnerabilitiesfire
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone
Sensesblindsight 120 ft. passive Perception 10
Languages-
Challenge 17 (18000 XP)
Greensickness.The plague brush is surrounded by a cloud of spores. Whenever a creature starts its turn within 30 feet of a plague brush (including creatures engulfed by it), that creature must make a DC 22 Constitution saving throw. On a successful save, the creature is immune to the Greensickness of all plague brushes for 24 hours. On a failed save, the creature is poisoned for 1 minute. A creature poisoned this way may repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Tumbling Trample. The plague brush can move through Large or smaller creatures’ spaces. Whenever the plague brush enters a creature’s space, that creature must make a DC 22 Dexterity saving throw. On a successful save, the creature is moved 5 feet to the side of the plague brush. On a failed save, the creature takes 14 (4d6) bludgeoning damage, and is engulfed by the plague brush. The engulfed creature is restrained. When the plague brush moves, the engulfed creature moves with it, and the engulfed creature takes 3 (1d6) bludgeoning damage for every 10 feet the plague brush moves. An engulfed creature can try to escape by taking an action to make a DC 22 Strength (Athletics) check. On a success, the creature escapes and enters a space of its choice within 5 feet of the plague brush. The plague brush can have up to ten creatures engulfed by it at a time.
Actions
Multiattack.The plague brush makes two slam attacks.
Slam.Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 21 (3d8+8) bludgeoning damage.

These monstrous tumbleweed-like creatures roll over the terrain of the layers of Carceri with a rustling like thunder. It overruns everything in its path, its only instinct to consume. They exude a cloud of spores that sickens those it sweeps up in its tangled grasp, as well as those it narrowly misses. These terrifying creatures measure up to 35 feet in diameter, and weigh up to 40 tons. 

Originally from the Monster Manual III

Yuan-Ti Ignan
Large monstrosity (yuan-ti), chaotic evil
Armor Class 15 (natural armor, shield)
Hit Points 104 (11d10 + 44)
Speed30 ft.
Str21,Dex13,Con18,Int6,Wis14,Cha11
SkillsDeception +3, Stealth +4
Damage Immunities fire
Damage Resistancespoison
Damage Vulnerabilities cold
Condition Immunitiespoisoned
Sensesdarkvision 120 ft. passive Perception 12
LanguagesAbyssal, Common, Draconic
Challenge7 (2900 XP)
Magic Resistance. The yuan-ti has advantage on saving throws against spells and other magical effects.
Magic Weapons. The yuan-ti’s weapon attacks are magical.
Actions
Multiattack. The yuan-ti makes four attacks: two with its mace, one with its gore, and one with its tail slap.
Mace.Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 12 (2d6+5) bludgeoning damage and 3 (1d6) fire damage.
Gore.Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 9 (1d8+5) piercing damage and 3 (1d6) fire damage.
Tail Slap. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 10 (1d10+5) bludgeoning damage and 3 (1d6) fire. If the target is a Large or smaller creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained, the yuan-ti can’t use its tail slap, and the target takes 15 (3d6+5) bludgeoning damage and 7 (2d6) fire damage at the start of each of the yuan-ti’s turns.

The result of crossbreeding between yuan-ti and salamanders, yuan-ti ignans are aggressive and brutal, with an affinity for fire. They are rarely enountered without greater yuan-ti as their masters, who consider them to be expendable. Fear of insurrection causes yuan-ti leadership to keep ignans apart from each other until they are ready to be fielded in battle. Some yuan-ti fortresses have fallen to ignan uprisings, and are occupied solely by the creatures. They tend to keep gems and coins as treasure; never flammable items. Yuan-ti ignans range between 10 and 14 feet long and weigh 250 to 400 lbs. The males tend to have red scales, while the females tend to have gray or brown scales. 

Originally from the Monster Manual IV.

Du'ulora Quori
Large aberration, lawful evil
Armor Class 17 (natural armor)
Hit Points 157 (15d10 + 75)
Speed5 ft., fly 70 ft. (hover)
Str23,Dex13,Con20,Int15,Wis18,Cha19
Saving Throws Dex +5, Int +6, Wis +8
SkillsArcana +6, Deception +8, Perception +12
Damage Immunitiesfire
Damage Resistances psychic; bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunities charmed, frightened
Sensesdarkvision 60 ft., passive Perception 22
Languages Common, Quori; telepathy 100 ft.
Challenge11 (7200 XP)
Empathic Aura. The quori has an intuitive awareness of the emotions and thoughts of creatures within 60 feet of it. It has advantage on Wisdom (Insight) checks made against those creatures. As a bonus action, the quori can choose to focus this empathy on a single creature within 60 feet of it. When it does, the quori can choose at the start of each of its turns to either grant itself advantage on attack rolls against that creature until the start of the quori’s next turn, or cause that creature to have disadvantage on attack rolls against the quori until the start of the quori’s next turn. This effect lasts for 1 minute, or until the quori uses a bonus action to switch targets.
Actions
Multiattack. The quori can use Burning Rage. It then makes three slam attacks.
Slam.Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 13 (2d6+6) bludgeoning damage and 3 (1d6) fire damage. If the target is a Large or smaller creature, it is grappled (escape DC 18).
Burning Rage. Each creature grappled by the quori must succeed on a DC 16 Wisdom saving throw or take 21 (6d6) fire damage. A creature that fails its save by 5 or more takes 35 (10d6) fire damage instead. If the quori kills a creature with this ability, the quori regains 10 hit points.

Also known as blackfuries, these quori are capable of driving beings’ innermost anger, exploiting it in battle, and even tapping into it such that the victim spontaneously combusts from sheer rage. It appears ghostly, yet is quite solid, grappling creatures with tentacles formed of shadow. 

Originally from Secrets of Sarlona.

Snowflake Ooze
Medium ooze, unaligned
Armor Class5
Hit Points 112 (15d8 + 45)
Speed15 ft., climb 5 ft.
Str16,Dex1,Con16,Int1,Wis6,Cha1
Damage Immunitiescold
Damage Resistances piercing
Damage Vulnerabilities fire
Condition Immunities blinded, charmed, deafened, exhaustion, frightened, grappled, prone, restrained
Sensesblindsight 60 ft. passive Perception 8
Languages-
Challenge5 (1800 XP)
Amorphous. The snowflake ooze can move through a space as narrow as 1 inch wide without squeezing.
Cold Aura. Whenever a creature starts its turn within 5 feet of the snowflake ooze, that creature takes 3 (1d6) cold damage.
Snow Camouflage. While the snowflake ooze remains motionless, it is indistinguishable from a normal patch of snow.
Actions
Multiattack. The snowflake ooze uses its Icy Embrace. It then makes two slam attacks.
Slam.Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d6+3) bludgeoning damage and 3 (1d6) cold damage. If the target is a Medium or smaller creature, it is grappled (escape DC 14). Until this grapple ends, the target is restrained, and is pulled into the snowflake ooze’s space.
Icy Embrace. Each creature grappled by the snowflake ooze must succeed on a DC 14 Constitution saving throw or take 10 (3d6) cold damage.

These oozes live in the most frigid wastes, lurking dormant until they detect the presence of warm-blooded creatures. Most commonly found in ice caves or even the open tundra, they seek to freeze any interlopers to their own temperature and feed off of their remains. Snowflake oozes are around 10 feet wide and weigh about 250 pounds.

Originally from the Monster Manual III

Twigjack
Tiny fey, chaotic evil
Armor Class 15 (natural armor)
Hit Points 45 (10d4 + 20)
Speed30 ft.
Str8,Dex16,Con15,Int11,Wis14,Cha13
SkillsStealth +7
Damage Vulnerabilitiesfire
Sensesdarkvision 60 ft. passive Perception 12
LanguagesCommon, Sylvan
Challenge3 (700 XP)
Bramble Jump. Once on each of its turns, while standing in an area of undergrowth, the twigjack can use 10 feet of its movement to magically teleport to an unoccupied space within 120 feet that it can see that also contains undergrowth.
Sneak Attack (1/Turn). The twigjack deals an extra 7 (2d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the twigjack that isn’t incapacitated and the twigjack doesn’t have disadvantage on the attack roll.
Actions
Multiattack.The twigjack makes two claw attacks.
Claw.Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit:5 (1d4+3) slashing damage.
Splinterspray (Recharge 6). The twigjack emits a spray of splinters in a 20 foot cone. Each creature in the area must make a DC 12 Dexterity saving throw, taking 14 (4d6) piercing damage on a failed save, or half as much damage on a successful one.

Twigjacks torment travelers through the oldest forests with the deepest roots, attacking settlements and any attempt at taming the wilderness. Yet even treants cannot stand the small creatures, who are nimble and adept at getting in the nooks and crannies of the great treants. Sometimes these tiny creatures attempt to impress a dryad, usually without much luck. They resent being seen as plants, and are occasionally pressed into service by goblins for their skill in forceful surprise attacks. 

Originally from the Pathfinder Bestiary 2.

Abyssal Ghoul
Medium undead, chaotic evil
Armor Class 17 (natural armor)
Hit Points 136 (16d8 + 64)
Speed40 ft.
Str21,Dex16,Con18,Int14,Wis15,Cha18
SkillsStealth +11
Damage Immunities electricity, poison
Damage Resistances acid, cold, fire
Condition Immunitiespoisoned
Sensesblindsight 90 ft. passive Perception 12
LanguagesAbyssal
Challenge10 (5900 XP)
Magic Resistance. The abyssal ghoul has advantage on saving throws against spells and other magical effects.
Sneak Attack (1/Turn). The abyssal ghoul deals an extra 17 (5d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the abyssal ghoul that isn’t incapacitated and the abyssal ghoul doesn’t have disadvantage on the attack roll.
Actions
Multiattack.The abyssal ghoul can use its Smoky Tongue. It then makes three attacks: two with its claws, and one with its talons.
Claw.Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 9 (1d8+5) slashing damage plus 9 (2d8) necrotic damage, and the target is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the abyssal ghoul can’t use the same claw to attack another target.
Talons.Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 12 (2d6+5) slashing damage plus 7 (2d6) necrotic damage. If the target is a creature, it must succeed on a DC 16 Constitution saving throw or contract a disease. Until the disease is cured, the target can’t regain hit points except by magical means, and the target’s hit point maximum decreases by 3 (1d6) every 24 hours. If the target’s hit point maximum drops to 0 as a result of this disease, the target dies. If the target succeds on its saving throw, it is immune to contracting the disease for 24 hours.
Smoky Tongue. One creature grappled by the abyssal ghoul must succeed on a DC 16 Wisdom saving throw or take 28 (8d6) psychic damage.
Reactions
Uncanny Dodge. The abyssal ghoul halves the damage that it takes from an attack that hits it. The abyssal ghoul must be able to see the attacker.

Humanoid, but with bizarre and twisted proportions, the abyssal ghoul looks much like a normal ghoul, but with some clearly demonic features. With scaly flesh, and a tongue trailing sickly smoke, these creatures hunt in deep caves of the Material Plane as well as part of the Abyss. In groups, they seek to outflank their opponents, attacking one target so as to distract it and make use of their sneak attack abilities. Abyssal ghouls are about the same height and weight as an adult human. 

Originally from the Fiend Folio. An anonymous request. 

Ragewalker
Large fey, neutral evil
Armor Class 18 (plate)
Hit Points 161 (17d10 + 68)
Speed50 ft.
Str19,Dex17,Con19,Int10.Wis14,Cha24
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunities charmed, frightened
Sensespassive Perception 12
LanguagesAbyssal, Common, Infernal, Sylvan
Challenge14 (11500 XP)
Magic Resistance. The ragewalker has advantage on saving throws against spells and other magical effects.
Blood Frenzy. Whenever a creature starts its turn within 10 feet of the ragewalker, that creature must make a DC 17 Wisdom saving throw. On a failed save, the creature is charmed. While charmed in this way, the creature flies into a mindless killing frenzy for 1 minute. While in this frenzy, the creature has advantage on attack rolls, and attack rolls against the creature have advantage. On each of its turns, the creature uses its movement to move to within 5 feet of the nearest creature to it, then it uses its action to make a melee attack against a randomly determined creature within its reach. The creature cannot talk or cast spells. An affected creature can repeat the saving throw at the end of each of its turns, ending the effect for itself on a success. A creature that succeeds on its save is immune to the Blood Frenzy of all ragewalkers for 24 hours
Weapon Cloud. The ragewalker is surrounded by a swarm of constantly whirling weapons. Whenever a creature moves within 5 feet of the ragewalker for the first time in a turn, or starts its turn within 5 feet of the ragewalker, that creature must succeed on a DC 17 Dexterity saving throw or take 13 (3d8) slashing damage.
Actions
Multiattack. The ragewalker makes three spiked chain attacks or two claw attacks.
Spiked Chain.Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 20 (3d10+4) slashing damage.
Claw.Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 9 (1d10+4) slashing damage.
Reactions
Repel Missiles. The ragewalker adds 5 to its AC against one ranged weapon attack that would hit it, potentially causing that attack to miss. If the attack misses, the attacker must succeed on a DC 16 Dexterity saving throw or take the damage from the attack as if hit by it. To do so, the ragewalker must see the attacker.

This strange metal-clad fey moves with sudden but graceful movements, a cloud of animate weapons orbiting it, spinning in a deadly, tantalizing dance. Ragewalkers embody the pain and grief of warfare, and the destruction it leaves on the natural landscape. They crusade ceaselessly against war by hunting down any capable of waging it. They can often be found wandering about old battlefields, using their blood frenzy aura to turn their foes against each other. Ragewalkers stand around 15 feet tall and weigh 500 pounds. 

Originally from the Monster Manual III. A request from infinite-non

Darkweaver
Medium aberration, neutral evil
Armor Class 16 (natural armor)
Hit Points 143 (22d8 + 44)
Speed25 ft., climb 25 ft.
Str17,Dex18,Con15,Int15,Wis16,Cha17
Saving Throws Con +6, Wis +7
Damage Resistances cold; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Vulnerabilitiesradiant
Condition Immunities charmed, frightened
Senses darkvision 120 ft. passive Perception 13
Languages Abyssal, Common, Infernal
Challenge10 (5900 XP)
Shadow Jump. While in dim light or darkness, the darkweaver can teleport as a bonus action up to 60 feet to an unoccupied space it can see that is also in dim light or darkness.
Shadow Shroud. The darkweaver is surrounded by swirling shadows. If the darkweaver starts its turn in dim light or darkness, the darkweaver has advantage on Dexterity (Stealth) checks and attack rolls against it have disadvantage until the start of its next turn.
Shadow Strands. Areas of dim light or darkness within 60 feet of the darkweaver are magically difficult terrain.
Sunlight Sensitivity. While in sunlight, the darkweaver has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.
Actions
Multiattack.The darkweaver makes three attacks with its tentacles, uses Reel, and makes one attack with its bite.
Bite.Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit:11 (2d6+4) piercing damage and 14 (4d6) necrotic damage. If the target is a creature, its Strength score is reduced by 1d4. The target dies if this reduces its Strength to 0. Otherwise, this reduction lasts until the target finishes a short or long rest.
Tentacle.Melee Weapon Attack: +8 to hit, reach 20 ft., one target. Hit: 7 (1d6+4) bludgeoning damage and 7 (2d6) necrotic damage. If the target is a creature, it is grappled (escape DC 15). Until the grapple ends, the target is restrained and has disadvantage on Strength checks and Strength saving throws, and the darkweaver can’t use the same tentacle on another target. The darkweaver has eight tentacles, each of which can grapple only one target.
Reel.The darkweaver pulls each creature grappled by it up to 20 feet straight toward it.

This writing mass looks a bit like a spider, with too many eyes and writhing tentacles instead of legs. They originate in the Shadowfell, but many come to the Material Plane to hunt, finding prey more plentiful there, and easier to catch. They often ally with other carnivores by feeding prey they trap to such creatures to build trust, eventually gaining the affection of such creatures. Often tribes of creatures, particularly trolls, to worship a darkweaver for its shadow powers, and help it in accomplishing its dark pursuits, which vary from one individual to another. Darkweavers are 4 to 5 feet tall and weigh around 250 pounds. 

Originally from the Fiend Folio

Nightmare Beast
Huge monstrosity, chaotic evil
Armor Class 17 (natural armor)
Hit Points 202 (15d12 + 105)
Speed30 ft.
Str24,Dex13,Con25,Int8,Wis13,Cha11
Saving Throws Dex +6, Con +12
Damage Resistances bludgeoning, piercing, and slashing from nonmagical attacks
Condition Immunitiesfrightened
Sensesdarkvision 60 ft. passive Perception 11
LanguagesAbyssal
Challenge15 (13000 XP)
Augmented Critical. The nightmare beast’s weapon attacks score a critical hit on a roll of 19 or 20.
Magic Resistance. The nightmare beast has advantage on saving throws against spells and other magical effects.
Nightmares. Humanoids within 10 miles of the nightmare beast that need to sleep are plagued by constant nightmares and can’t gain the benefits of a long rest while they remain in the area.
Actions
Multiattack.The nightmare beast makes four attacks: one with its tusks, one with its bite, and two with its claws.
Bite.Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit:20 (3d8+7) piercing damage.
Tusks.Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 23 (3d10+7) piercing damage.
Claws.Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit:17 (3d6+7) slashing damage.
Dread Trample. The nightmare beast moves up to its speed. During this movement, it can move through the spaces of Large or smaller creatures. A creature whose space the nightmare beast enters for the first time on a turn must make a DC 20 Dexterity saving throw, taking 44 (8d10) bludgeoning damage on a failed save, or half as much damage on a successful one. At the end of this movement, it may make one attack with its tusks.

The nightmare beast is a terrifying creature with tough dark gray hide with blue, purple, and brown spots splattered across it. Its beady red eyes glow in the dark. The nightmare beast lives in a cave deep in the wastes, picking the region clean of prey before hibernating for a year or more. After awakening, it is often so ravenous that its hunting spree drives all civilized life out of its territory. The nightmare beast does not collect treasure; the only treasure that is usually found in its lair is that which it has eaten in its rush to consume its prey. A nightmare beast stands around 20 feet tall. Its weight is unknown.

Originally from the Monster Manual II

Night Twist
Large plant, neutral evil
Armor Class 14 (natural armor)
Hit Points 231 (22d10 + 110)
Speed 10 ft.
Str25,Dex6,Con21,Int12,Wis14,Cha19
Damage Resistances bludgeoning, piercing
Damage Vulnerabilitiesfire
Condition Immunities blinded, deafened, exhaustion
Senses darkvision 120 ft., tremorsense 60 ft. passive Perception 12
Languages understands Common, Elven, and Sylvan, but cannot speak
Challenge 12 (8400 XP)
Death Curse. When the night twist is killed, the creature that killed it must succeed on a DC 16 Wisdom saving throw or be cursed. The curse causes the creature’s sleep to be plagued with nightmares. If the creature needs to sleep, it is unable to, and gains one level of exhaustion each morning. After gaining a level of exhaustion, an affected creature may repeat the saving throw, ending the effect for itself on a success. A remove curse spell cast on the creature also ends the effect for that creature. If an affected creature dies before the curse is removed, and its remains are buried, a new night twist begins to grow on the site of its grave after 1 month.
Song Of Despair. While it is night, the night twist constantly emits a sorrowful song, which can be heard up to 1200 feet from it. Whenever a creature that can hear the song enters within 1200 feet of the night twist, that creature must make a DC 16 Wisdom saving throw. On a successful save, the creature is immune to the Song of Despair of all night twists for 24 hours. On a failed save, the creature is charmed by the night twist. While charmed in this way, the creature moves toward the night twist, and takes no other actions. When it reaches the night twist, it stands within 5 feet of it, taking no action. If a remove curse spell is cast on the affected creature, the effect ends. If an affected creature takes damage, it may repeat the save, ending the effect on itself on a success.
Actions
Multiattack.The night twist can use Wind Blast if it is able to. It then makes three slam attacks.
Slam.Melee Weapon Attack: +11 to hit, reach 10 ft., one creature. Hit:20 (3d8+7) bludgeoning damage.
Wind Blast (Recharge 5-6). A powerful wind emanates from the night twist, extinguishing all open flames within 120 feet of it. Each creature within that radius must succeed on a DC 17 Strength saving throw or be knocked prone.

Often, travelers through the dark forests and marshes of the world will hear a haunting melody wafting through the trees. The song always sounds like the most sorrowful thing the listener can imagine; it never sounds alike to two different people. What they can all agree on is its allure, magically drawing toward the old, dead-looking, twisted tree that sings it. There, the night twist attacks its prey, consuming the festering corpses that remain. Night twists stand around 15 feet tall and weigh at least 6,000 pounds. They do not seem to die naturally, though no one knows for sure. The older the night twist, the larger it grows, and the truly ancient ones are said to have attained massive size, and are far more formidable. 

Originally from the Monster Manual III

Slaughterstone Eviscerator
Large construct, unaligned
Armor Class 22 (natural armor)
Hit Points 112 (15d10 + 30)
Speed30 ft.
Str23,Dex11,Con14,Int2,Wis11,Cha1
Damage Immunities poison, psychic; bludgeoning, piercing and slashing from nonmagical attacks that aren’t adamantine
Damage Resistances acid, cold, fire, lightning
Condition Immunities charmed, deafened, exhaustion, frightened, petrified, poisoned, stunned
Sensesdarkvision 60 ft. passive Perception 10
Languages understands the languages of its creator but can’t speak
Challenge12 (8400 XP)
Adamantine Weapons. The slaughterstone eviscerator’s weapon attacks are adamantine.
Keen Blades. The slaughterstone eviscerator’s attacks score a critical hit on a roll of 19 or 20.
Magic Resistance. The slaughterstone eviscerator has advantage on saving throws against spells and other magical effects.
Actions
Multiattack. The slaughterstone eviscerator makes four attacks with its adamantine blades.
Adamantine Blade.Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 17 (2d10+6) slashing damage.
Slashing Whirlwind (Recharge 6). Each creature within 10 feet of the slaughterstone eviscerator must make a DC 18 Dexterity saving throw, taking 50 (8d10+6) slashing damage on a failed save, or half as much damage on a successful one.

These terrifying stone dervishes were first created by the dwarves as war machines, but the secret to their creation has escaped their careful guardianship, and spread to others. This construct can tear through an entire battalion of enemy soldiers. The duergar are said to have learned the secret of building slaughterstone eviscerators, and dwarves warn they will use one in a surface raid before long. Slaughterstone eviscerators give off no odor, and make no noise but the occasional creaking of their joints as they move.

Originally from the Monster Manual III.

Hellfire Wyrm
Huge dragon, lawful evil
Armor Class 22 (natural armor)
Hit Points 405 (30d12 + 210)
Speed 50 ft., burrow 30 ft., fly 90 ft.
Str27,Dex10,Con25,Int20,Wis21,Cha25
Saving Throws Dex +8, Con +16, Wis +14, Cha +15
Skills Deception +14, Perception +13
Damage Immunities fire; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Vulnerabilitiescold
Condition Immunities paralyzed
Senses passive Perception 23, truesight 120 ft.
Languages Common, Draconic, Infernal
Challenge 26 (90000 XP)
Infernal Aura. At the start of each of the wyrm’s turns, each creature within 5 feet of it takes 10 (3d6) fire damage, and flammable objects in the aura that aren’t being worn or carried ignite. A creature that touches the wyrm or hits it with a melee attack while within 5 feet of it takes 10 (3d6) fire damage. The wyrm can suppress or resume this aura as a bonus action.
Legendary Resistance (3/Day). If the wyrm fails a saving throw, it can choose to succeed instead.
Magic Resistance. The wyrm has advantage on saving throws against spells and other magical effects.
Innate Spellcasting. The hellfire wyrm’s spellcasting ability is Charisma (spell save DC 23). The hellfire wyrm can innately cast the following spells, requiring no material components:
At will: charm person, hold person, sending, wall of fire
1/day each: greater invisibility, meteor swarm
Actions
Multiattack. The wyrm can use its Frightful Presence. It then makes six attacks: one with its bite, four with its claws, and one with its tail.
Bite.Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit:27 (4d8+9) piercing damage plus 14 (4d6) necrotic damage.
Claw.Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 18 (2d8+9) slashing damage plus 10 (3d6) necrotic damage.
Tail.Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 21 (3d8+8) bludgeoning damage plus 10 (3d6) necrotic damage. If the target is a creature, it must succeed on a DC 24 Strength saving throw or be knocked prone.
Fiendish Form. The wyrm magically polymorphs into a Small or Medium fiend, or back into its true form. Its statistics are the same in each form. Any equipment it is wearing or carrying isn’t transformed. It reverts to its true form if it dies.
Frightful Presence. Each creature of the wyrm’s choice that is within 120 feet of the wyrm and aware of it must succeed on a DC 22 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the wyrm’s Frightful Presence for the next 24 hours.
Hellfire Breath (Recharge 5-6). The wyrm exhales fire in a 50-foot cone. Each creature in the area must make a DC 23 Dexterity saving throw, taking 44 (8d10) fire damage and 44 (8d10) necrotic damage on a failed save, or half as much damage on a successful one.
Summon Fiend (1/Day). The wyrm summons a horned devil, barbed devil, or bone devil to aid it in battle. The devil appears within 60 feet of the wyrm. Roll initiative for the devil, which has its own turns. It remains for 1 minute, or until dismissed by the wyrm as a bonus action. The devil obeys the wyrm’s orders, which it can issue at the start of each of its turns.

These dread dragons are servants of the most powerful devils, even exceeding many of them in power. They often spend time in the form of a humanoid, manipulating rulers of nations into doing their bidding. Others rule as outright tyrants. In its true form, a hellfire wyrm’s eyes glow yellow, smoke billows constantly from its body, and it is surrounded by a sulfurous stench. Few creatures can stand up to a hellfire wyrm in combat, and in the rare instance the creature does find itself outmatched, it will retreat to one of its numerous secret lairs to plot its revenge.

Originally from the Monster Manual II

Dunewinder
Huge monstrosity, unaligned
Armor Class 16 (natural armor)
Hit Points 178 (17d12 + 68)
Speed 50 ft., burrow 20 ft.
Str23,Dex15,Con19,Int5,Wis12,Cha11
Damage Immunitiesfire
Damage Resistances necrotic, poison
Damage Vulnerabilitiescold
Condition Immunities blinded, prone
Sensestremorsense 60 ft. passive Perception 11
Languages-
Challenge10 (5900 XP)
Death Throes. When the dunewinder dies, it explodes, and each creature within 60 feet of it must make a DC 16 Dexterity saving throw, taking 17 (5d6) piercing damage and 17 (5d6) poison damage on a failed save, or half as much damage on a successful one. 
Actions
Bite.Melee Weapon Attack: +8 to hit, reach 10 ft., one target.Hit: 22 (3d10+6) piercing damage. The target must make a DC 16 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one. The target is grappled (escape DC 18). Until this grapple ends, the target is restrained, and the dunewinder can’t use its bite on another target.
Fire Breath (Recharges After A Short Or Long Rest). The dunewinder exhales fire in a 60-foot line that is 10 feet wide. Each creature in that line must make a DC 16 Dexterity saving throw, taking 49 (14d6) fire damage on a failed save, or half as much damage on a successful one.

The desert cousins of the arctic remorhaz, dunewinders are named for their sidewinding motions as they travel through the sand. They prefer to weaken prey with a blast of their fire breath, before biting and strangling them to finish them off. Often, they lie in ambush just over the crest of a dune, waiting for prey to approach. These creatures are always encounters alone. Dunewinders can be up to 40 feet long.

Originally from Sandstorm

For a compilation of all of the monster stats so far posted here, visit this Pastebin link: https://pastebin.com/raw/YtEQ4LMA

Digester
Medium monstrosity, unaligned
Armor Class 14 (natural armor)
Hit Points 119 (14d8 + 56)
Speed60 ft.
Str17,Dex15,Con18,Int2,Wis12,Cha10
SkillsStealth +5
Damage Immunitiesacid
Sensesdarkvision 60 ft. passive Perception 11
Languages-
Challenge6 (2300 XP)
Keen Smell. The digester has advantage on Wisdom (Perception) checks that rely on smell.
Standing Leap. The digester’s long jump is up to 30 feet and its high jump is up to 15 feet, with or without a running start.
Actions
Multiattack.The digester makes two bite attacks.
Bite.Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 10 (2d6+3) piercing damage plus 10 (3d6) acid damage.
Acid Spray (Recharge 5-6). The digester sprays acid in a 30-foot cone. Each creature in that area must make a DC 14 Dexterity saving throw, taking 42 (12d6) acid damage on a failed save, or half as much damage on a successful one.

A digester is almost constantly hungry, though its insatiable appetite does not prevent it from being a cunning and patient hunter. It waits in ambush, springing on its foes and unleashing a spray of acid, and then biting and snapping until it acid glands refill. They are usually solitary, but packs of up to a half-dozen individuals have been recorded. They tend to live in tropical forests and hills, where its prey are most plentiful. A digester stands about 5 feet tall and is 7 feet long from snout to tail. It weighs about 350 pounds,

Originally from the Monster Manual.

Desert Devil
Medium fiend (devil), lawful evil
Armor Class 14 (natural armor)
Hit Points 105 (14d8 + 42)
Speed30 ft.
Str15,Dex15,Con16,Int6,Wis10,Cha12
Saving Throws Dex +5, Con +6, Wis +3
Damage Immunities fire, poison
Damage Resistances cold; bludgeoning, piercing, and slashing from nonmagical attacks that aren’t silvered
Sensesdarkvision 120 ft. passive Perception 10
LanguagesInfernal, telepathy 120 ft.
Challenge6 (2300 XP)
Desert Halo. Sand constantly swirls around the devil. Whenever a creature enters within 10 feet of the devil for the first time in a turn, or starts its turn within 10 feet of the devil, that creature takes 7 (2d6) slashing damage.
Devil’s Sight. Magical darkness doesn’t impede the devil’s darkvision.
Infernal Savagery. A melee weapon deals one extra die of its damage when the devil hits with it (included in the attack).
Magic Resistance. The devil has advantage on saving throws against spells and other magical effects.
Actions
Multiattack. The desert devil makes two scimitar attacks.
Scimitar.Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 9 (2d6+2) slashing damage.
Whirlwind Attack (Recharge 5-6). The desert devil makes one scimitar attack against each creature it can reach.

Sand constantly swirls around these creatures as they patrol the desert, excoriating their flesh. Also known as aratons, desert devils always travel alone, appearing as a mere dust cloud from far away, but as they approach it becomes clear they are something far worse.  A desert devil stands around 6 feet tall and weighs 190 lbs.

Originally from Sandstorm.