Quarut Medium construct (inevitable), lawful neutral Armor Class 18 (plate) Hit Points 189 (18d8 + 108) Speed 50 ft. Str 20, Dex 13, Con 23, Int 14, Wis 17, Cha 20 Saving Throws Dex +7, Int +8, Wis +9 Skills Perception +9 Damage Immunities poison, psychic; bludgeoning, piercing, and slashing from nonmagical attacks that aren't adamantine Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned, stunned, unconscious Senses truesight 120 ft., passive Perception 19 Languages all Challenge 17 (18000 XP) Magic Resistance. The quarut has advantage on saving throws against spells and other magical effects. Rapid Reconstruction. At the beginning of each of the quarut's turns, if it has at least 1 hit point, it regains 15 hit points. Immutable Form. The quarut is immune to any spell or effect that would alter its form. Innate Spellcasting. The quarut's spellcasting ability is Charisma (spell save DC 19). The quarut can innately cast the following spells, requiring no material components: At will: dimension door, dispel magic, dominate person, haste, hold monster, locate creature 1/day each: forcecage, teleport, time stop Actions Multiattack. The quarut makes two slam attacks. Slam. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 15 (3d6+5) bludgeoning damage plus 31 (7d8) force damage.

Quaruts are inevitables tasked with preserving the integrity of time and space. They usually target wizards who make excessive use of time stop and wish spells; however, the quaruts have no qualms about using such spells themselves. Their bodies are covered in finely-etched plates, beneath which are various intricate mechanical time pieces. Their head contains an hourglass whose glowing sands constantly flow upward for some inexplicable reason. Quaruts mercilessly hunt down spellcasters who flagrantly violate the laws of time and space, always working alone to bring down their quarry.

Originally from the Fiend Folio.

Hellfire Golem Large construct, lawful evil Armor Class 20 (natural armor) Hit Points 241 (21d10 + 126) Speed 40 ft. Str 25, Dex 14, Con 22, Int 12, Wis 13, Cha 14 Damage Immunities fire, poison, psychic; bludgeoning, piercing, and slashing from nonmagical attacks not made of adamantine Damage Resistances acid, cold Senses darkvision 60 ft. passive Perception 11 Languages Infernal Challenge 17 (18000 XP) Body Of Flame. A creature that touches the golem or hits it with a melee attack while within 5 feet of it takes 10 (3d6) fire damage. Illumination. The golem sheds bright light in a 30-foot radius and dim light in an additional 30 feet. Immutable Form. The golem is immune to any spell or effect that would alter its form. Magic Resistance. The golem has advantage on saving throws against spells and other magical effects. Magic Weapons. The golem's weapon attacks are magical. Water Susceptibility. For ever 5 feet the golem moves in water, or for ever gallon of water splashed on it, it takes 1 cold damage. Innate Spellcasting. The hellfire golem's spellcasting ability is Charisma (spell save DC 16). The hellfire golem can innately cast the following spells, requiring no material components: At will: burning hands, fireball, produce flame 3/day each: flame strike Actions Multiattack. The golem makes two slam attacks. Slam. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 20 (3d8+7) bludgeoning damage plus 16 (3d10) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns. Fire damage dealt by this attack, or from being on fire from it, ignores resistance to fire damage.

These massive golems resemble a walking funeral pyre, though one that burns hotter than any in the mortal world. They are created by devils with a pyromaniacal bent, and in fact can only be successfully created in the Nine Hells, with special clay found only there. They are not mindless, but are unsubtle either, preferring to burn their foes to death as directly as possible, blasting them with fireball and flame strike spells while closing in to melee. 

Originally from the Fiend Folio

Plague Brush Gargantuan plant, unaligned Armor Class 12 (natural armor) Hit Points 333 (18d20 + 144) Speed 60 ft. Str 27. Dex 10, Con 26, Int 1, Wis 11, Cha 10 Damage Resistances piercing Damage Vulnerabilities fire Condition Immunities blinded, charmed, deafened, exhaustion, frightened, prone Senses blindsight 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

Effigy Medium undead, chaotic evil Armor Class 15 Hit Points 175 (27d8 + 54) Speed 0 ft., fly 60 ft. (hover) Str 7, Dex 21, Con 15, Int 16, Wis 17, Cha 17 Damage Immunities fire, necrotic, poison Damage Resistances acid, lightning, thunder; bludgeoning, piercing, and slashing from nonmagical attacks that aren't silvered Damage Vulnerabilities cold Condition Immunities charmed, exhaustion, frightened, grappled, paralyzed, petrified, unconscious Senses darkvision 60 ft. passive Perception 13 Languages Abyssal, telepathy 100 ft. Challenge 17 (18000 XP) Incorporeal Movement. The effigy 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. Magic Resistance. The effigy has advantage on saving throws against spells and other magical effects. Actions Multiattack. The effigy can use Infuse. It then makes two attacks with its Rotfire Touch Rotfire Touch. Melee Weapon Attack: +11 to hit, reach 5 ft., one creature. Hit: 27 (4d10+5) necrotic damage plus 22 (4d10) fire damage. Infuse. One humanoid that the effigy can see within 5 feet of it must succeed on a DC 17 Charisma saving throw or be infused with the effigy; the effigy then occupies the same space as the target, and the target is incapacitated and loses control of its body. The effigy now controls the body but doesn’t deprive the target of awareness. The effigy can’t be targeted by any attack, spell, or other effect, except ones that turn undead, and it retains its alignment, Intelligence, Wisdom, Charisma, and immunity to being charmed and frightened. It otherwise uses the infusion target’s statistics, except that the target deals an extra 7 (2d6) fire damage with each of its melee attacks, and the target takes 7 (2d6) fire damage at the start of each of its turns. The infusion lasts until the body drops to 0 hit points, the effigy ends it as a bonus action, or the effigy is turned or forced out by an effect like the dispel evil and good spell. When the infusion ends, the effigy reappears in an unoccupied space within 5 feet of the body. The target is immune to this effigy's Infuse for 24 hours after succeeding on the saving throw or after the infusion ends.

Effigies are fiery undead spirits who hate life and seek to consume its energy, wreathing victims in flame and using them to slay others until its host is entirely immolated.  It appears as a translucent humanoid shape with faint white-glowing eyes within its body, but no other discernible facial features.

Originally from the Monster Manual II.  If there is a monster from 3.5 or Pathfinder that you want to see converted to 5e, feel free to send me a message or submit a monster request on the submit page. I have gotten to many requests, many are works in progress and are completed but simply need workshopping before release.

Merchurion Huge construct, chaotic evil Armor Class 20 (natural armor) Hit Points 220 (21d12 + 84) Speed 60 ft. Str 25, Dex 23, Con 19, Int 10, Wis 14, Cha 17 Saving Throws Dex +12, Con +10, Wis +8 Damage Immunities fire, poison; bludgeoning, piercing, and slashing from nonmagical attacks that aren't silvered Damage Vulnerabilities thunder Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned Senses darkvision 60 ft. passive Perception 12 Languages Common, Giant, Terran Challenge 17 (18000 XP) Absorb Enchantment. Whenever a merchurion is hit by a magical weapon with a bonus to attack and damage rolls, decrease that weapon's bonus by 1 (to a minimum of 0), and increase the bonus on attack and damage rolls of the merchurion's battleaxe by 1 (to a maximum of +3). A magical weapon whose bonus is reduced to 0 by the merchurion becomes nonmagical. In addition, if the magical weapon has any other special properties, the merchurion's battleaxe gains those properties, but they are not removed from the original weapon unless it becomes nonmagical. These changes last for 1 hour, or until the merchurion dies. Magic Weapons. The merchurion's weapon attacks are magical. Actions Multiattack. The merchurion can use Generate Weapon. It then makes four melee attacks. Silvered Battleaxe. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 25 (4d8+7) slashing damage. If the merchurion scores a critical hit, and the target is a Medium or smaller creature, the target must succeed on a DC 21 Strength saving throw or be knocked 10 feet away from the merchurion, fall prone, and take 7 (2d6) bludgeoning damage. Generate Weapon. The merchurion generates a silvered battleaxe from its body. If this weapon leaves the merchurion's grasp, it melts into a pool of harmless silver liquid, and the merchurion loses 5 hit points.

The merchurions are said to have once been fire giants, master smiths in the service of their god. They worked for years to produce a metal stronger than adamantine; when they failed, they were flung into the magma pits by their disappointed god. When they emerged, their souls had embodied the metal, forming them into living constructs of quicksilver. The last remnants of an ancient age, these creatures wander through the mountains, devouring metal. A group of armed travelers will likely attract their attention. Merchurions despise true giants and will almost always attack them. Parlay with merchurions is almost impossible. They are savage combatants, driven partly by their shame over failing their god and their resulting punishment. They are almost always alone, but on the rare occasion they gather in groups, those groups number no more than six. Merchurions also seek out those with knowledge of crafting constructs. With no way to reproduce, the merchurions die off one by one as they are killed, though they do not age and are said to be thousands of years old. When a merchurion is killed, it melts into a puddle of silver which evaporates after 24 hours. Any weapon dipped in this silver becomes magical and silvered permanently. A merchurion stands 20 feet tall and weighs 12 tons. 

Originally from the Monster Manual V.  If there is a monster from 3.5 or Pathfinder that you want to see converted to 5e, feel free to send me a message or submit a monster request on the submit page. I have gotten to many requests, many are works in progress and are completed but simply need workshopping before release.

Deathbringer Large undead, neutral evil Armor Class 17 (half plate) Hit Points 241 (21d10 + 126) Speed 40 ft. Str 20, Dex 15, Con 23, Int 13, Wis 14, Cha 7 Saving Throws Dex +8, Con +12, Wis +8 Skills Intimidation +4, Perception +8, Stealth +8 Damage Immunities poison Damage Resistances necrotic Condition Immunities exhaustion, frightened, poisoned Senses darkvision 60 ft., passive Perception 18 Languages Common, Abyssal Challenge 17 (18000 XP) Indomitable (3/Day). The deathbringer can reroll a saving throw it fails. It must use the new roll. Trample. The deathbringer can move through the space of a prone creature. A creature whose space the deathbringer enters for the first time on a turn must make a DC 19 Dexterity saving throw, taking 18 (4d8) bludgeoning damage on a failed save, or half as much damage on a successful one. Actions Multiattack. The deathbringer makes four attacks with its flail, or two slam attacks. Flail. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 14 (2d8+5) bludgeoning damage plus 9 (2d8) necrotic damage. If the target is a Large or smaller creature, it must succeed on a DC 19 Strength or be knocked prone. Slam. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 12 (2d6+5) bludgeoning damage plus 9 (2d8) necrotic damage. Necrotic Burst (Recharge 6). Each non-undead creature within 20 feet of the deathbringer must make a DC 20 Constitution saving throw, taking 55 (10d10) necrotic damage on a failed save, or half as much damage on a successful one.

Deathbringers serve as generals for liches, demons, and necromancers, leading entire armies of powerful undead. They have little subtlety, and are loyal only as a means to inflict death and destruction on the living. They have gray skin, and their eyelids and lips have been sewn shut. 

Originally from the Monster Manual II.  If there is a monster from 3.5 or Pathfinder that you want to see converted to 5e, feel free to send me a message or submit a monster request on the submit page. I have gotten to many requests, many are works in progress and are completed but simply need workshopping before release.

Winterwight Medium undead, chaotic evil Armor Class 20 (natural armor) Hit Points 230 (20d8 + 140) Speed 30 ft. Str 27, Dex 23, Con 24, Int 11, Wis 22, Cha 25 Damage Immunities cold, necrotic, poison; bludgeoning, piercing, and slashing from nonmagical attacks Damage Vulnerabilities fire Condition Immunities charmed, exhaustion, frightened, paralyzed, poisoned, stunned Senses darkvision 60 ft. passive Perception 16 Languages Common, Infernal Challenge 17 (18000 XP) Aura Of Burning Cold. Whenever a creature that isn't an undead starts its turn within 10 feet of the winterwight, that creature takes 11 (2d10) cold damage. Magic Resistance. The winterwight has advantage on saving throws against spells and other magical effects. Sunlight Sensitivity. While in sunlight, the winterwight has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight. Innate Spellcasting. The winterwight's spellcasting ability is Charisma (spell save DC 21). The winterwight can innately cast the following spells, requiring no material components: At will: dimension door, sleet storm, wall of ice

Actions Multiattack. The winterwight makes two claw attacks. Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 21 (3d8+8) slashing damage plus 18 (4d8) cold damage, and the winterwight regains hit points equal to half the cold damage taken. If the target is a creature, it must succeed on a DC 24 Constitution saving throw or its hit point maximum is reduced by an equal amount to the damage taken. This reduction lasts until the target finishes a long rest. If this effect reduces the target's hit point maximum to 0, it dies, and its body is destroyed, leaving behind nothing but icy fragments. Breath Of Winter (Recharge 6). The winterwight breathes freezing air in a 30-foot cone. Each creature in that area must make a DC 23 Dexterity saving throw, taking 56 (16d6) cold damage on a failed save, or half as much damage on a succesful one. A creature that fails its save is also restrained until the end of its next turn.

Formed from the souls of those who died in the direst of winters, winterwights hunt in the tundra for victims to claim with their frigid, life-draining claws. They stand around 7 feet tall, their icy armor interwoven with their frozen muscle to form an impenetrable shell. These creatures revel in their victims’ suffering. They are often found alone or in pairs, but on rare occasions groups of several can be found. Evil deities of cold sometimes use them as heralds or assassins.

Originally from the 3rd Edition Epic Level Handbook, and the Pathfinder Bestiary 2.  If there is a monster from 3.5 or Pathfinder that you want to see converted to 5e, feel free to send me a message or submit a monster request on the submit page.

Happy holidays to all of my followers!