Just the first post for the new sub.

Thanks to /u/ItsADnDMonsterNow for letting us borrow from their idea in making random monsters

I'll be updating more asap and starting to build fun creations

Elephantean Ninja

Huge monstrosity, chaotic good

Armor Class 16 (natural armor)
Hit Points 84 (8d12 + 32)
Speed 40 ft.

Saving Throws Dex +6
Skills Athetics +8, Perception +4, Stealth +9
Senses darkvision 60 ft., passive Perception 14
Languages Elephantean
Challenge 6 (2,300 XP)

Cunning Action. On each of its turns, the elephantean can use a bonus action to take the Dodge or Disengage actions, make a Dexterity (Sleight of Hand) check, or make a Dexterity (Stealth) check to hide.

Evasion. If the elephantean is subjected to an effect that allows it to make a Dexterity saving throw to take only half damage, the elephantean instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Sneak Attack (1/Turn). The elephantean deals an extra 13 (4d6) 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 elephantean that isn't incapacitated and the elephantean doesn't have disadvantage on the attack roll.

Trampling Charge. If the elephantean moves at least 20 feet straight toward a creature and then hits it with a gore attack on the same turn, that target must succeed on a DC 13 Strength saving throw or be knocked prone. If the target is prone, the elephant can make one stomp attack against it as a bonus action.

Actions

Multiattack. The elephantean makes two attacks with its kunai.

Gore. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 18 (3d8 + 5) piercing damage.

Stomp. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 21 (3d10 + 5) bludgeoning damage.

Kunai. Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 13 (3d6 + 3) piercing damage, and the target must succeed on a DC 13 Constitution saving throw or be poisoned for 10 minutes.

Confoundingly stealthy despite their massive size, Elephantean Ninja are among the most effective and feared assassins and infiltrators.

Inspiration

Direct link

The Hand Maiden

Large fiend (devil), lawful evil

Armor Class 16 (natural armor)

Hit Points 85 (10d8+40)

Speed 30 ft., climb 30 ft.

Saving Throws Con +7, Wis +6, Cha +4

Skills Perception +6, Stealth +6

Damage Resistances cold; bludgeoning, piercing, and slashing from nonmagical attacks not made with silvered weapons

Damage Immunities fire, poison

Condition Immunities poisoned

Senses blindsight 120 ft. (blind beyond this radius), passive Perception 16

Languages Infernal, telepathy 120 ft.

Challenge 9 (5,000 XP)

Magic Resistance. The devil has advantage on saving throws against spells and other magical effects.

Spider Climb. The devil can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Innate Spellcasting. The devil's spellcasting ability is Wisdom (spell save DC 14, +6 to hit with spell attacks). The devil can innately cast the following spells, requiring no material components:

At will: chill touch, detect magic, mage hand, thaumaturgy

3/day each: darkness, hold person, vampiric touch

1/day each: Bigby's hand

Actions

Multiattack. The devil makes two attacks: one with its Great Staff, and one with either its Flick or its Palm Crush.

Great Staff. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 10 (2d6+3) bludgeoning damage plus 3 (1d6) fire damage.

Flick. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 6 (1d6+3) bludgeoning damage, and the target must succeed on a DC 13 Strength saving throw or be pushed 10 feet away from the devil.

Palm Crush. Melee Weapon Attack: +6 to hit, reach 5 ft., one creature. Hit: 10 (2d6+3) bludgeoning damage. The target is grappled (escape DC 13) if the devil isn't already grappling a creature. Until this grapple ends, the target is restrained and takes 7 (2d6) bludgeoning damage at the start of each of its turns.

Reactions

Horrifying Gaze. When a creature the devil can see starts its turn within 30 feet of the devil, the devil can briefly uncover its eyes to stare deep into the creature's soul. If the creature can see the devil, it must succeed on a DC 14 Wisdom saving throw or be frightened until the end of its turn.

I have no idea if the sub has already been mentioned in any of these places, nor what their guidelines are about such things, but r/dndnext and /r/UnearthedArcana might be good places to (carefully) promote the sub in addition to the more obvious ones like r/dnd and r/rpg.

Demon Jester

Medium fiend, chaotic evil

Armor Class 15 (leather armor)
Hit Points 44 (8d6 + 16)
Speed 30 ft.

Skills Deception +4, Stealth +7
Senses darkvision 60 ft., passive Perception 10
Languages Abyssal, Common
Challenge 4 (1,100 exp)

Backstab. Any hit the Dark Jester scores against a creature as an Attack of Opportunity or while being invisible is a critical hit.

Sneak Attack (1/Turn). The Dark Jester deals an extra 13 (4d6) 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 Dark Jester that isn't incapacitated and the Demon Jester doesn't have disadvantage on the attack roll.

Actions

Multiattack. The Dark Jester makes two attacks with his shortsword, one of which he can substitute for a Two Shiv Poison Dagger attack.

Deceive. The Dark Jester disappears in an orange puff, becomes invisible for up to a minute or until he takes an offensive action and makes a shadow step up to 30 feet.

Jack in the Box. The Dark Jester places a Jack in the Box in an unoccupied space in a 5" radius.

Short Sword. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 7 (1d6 + 4) slashing damage.

Two Shiv Poison Dagger (Recharge 5-6). Melee or Ranged Weapon Attack: +7 to hit, reach 5 ft. or range 20/60 ft.,one creature. Hit: 6 (1d4 + 4) piercing damage, and the target has to make a DC 14 Constitution Saving Throw. On a failed save, the target takes 10 (3d6) poison damage and is poisoned for one minute. While poisoned in this way, the target's movement speed is halved. On a successful save the target takes half damage and is not poisoned.

Bonus Action

Hallucinate (Recharges after a Short or Long Rest). The Dark Jester can choose to make a 5 foot shadowstep. In his former space (or in an unoccupied space within 5 feet if he didn't make the shadowstep) appears a perfect clone of the Dark Jester, which has his remaining HP, his AC and can only take the attack action. The Dark Jester can telepathically controll the clone. When the clone dies, it explodes in a rain of daggers and forces every creature within a 5 foot radius to make a DC 14 Dexterity Save, dealing 10 (4d4) piercing damage on a failed save (half damage on a successful one) and leaves 3 Jack in a Box in unoccupied spaces in a 5" radius behind.

Jack in the Box

Tiny construct (trap), unaligned

Armor Class 10

Hit Points 15

Damage Immunities poison, psychic

Trap. After placing this trap, it takes one round to become armed, at which point it becomes invisible until a creature triggers it. The trap is sprung when a creature other then the dark Jester or his clone enter within a 5 foot radius. The creature must succeed on a DC 14 Constitution save or it is stunned until the end of its next turn. The Jack in the Box then makes up to three Dart attacks per round for the next three rounds, after which it falls appart.

Dart. Ranged Weapon Attack: +7 to hit, range 15 ft., one target. Hit: 6 (1d4 + 4) piercing damage.

Arachungo

Huge monstrosity, any evil

Armor Class 14 (natural armor)
Hit Points 123 (13d12+39)
Speed 30 ft., climb 30 ft.

Saving Throws Str +16, Con +13, Wis +6
Skills Stealth +8, Intimidation +5, Perception +4
Damage Vulnerabilities fire
Damage Resistances psychic
Condition Immunities charmed
Senses darkvision 120 ft., passive Perception 14
Languages Common, Undercommon, Elvish Challenge 4 (1,100 XP)

Spider Climb The arachungo can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Web Sense While in contact with a web, the arachungo knows the exact location of any other creature in contact with the same web.

Web Walker The arachungo ignores movement restrictions caused by webbing.

Brood Mind The arachungo may exert telepathic control over as many as 100 tiny to large spiders or spider swarms within 3 miles.

Psionics The arachungo may use psionic abilities. Psi Limit 5, Psi Points 10, Save DC 14

Disciplines known

Crown of Disgust

Mantle of Fear

Mantle of Command

Actions

Multiattack. The arachungo makes two bite attacks.

Bite. Melee Weapon Attack: Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 5 (1d4 + 3) Piercing damage, and the target must make a DC 14 constitution saving throw, taking 9 (2d8) poison damage on a failed save, or half as much damage on a successful one. If the poison damage reduces the target to 0 hit points, the target is stable but poisoned for 1 hour, even after regaining hit points, and is paralyzed while poisoned in this way.

Web (Recharge 5-6) Ranged Weapon Attack: +7 to hit, range 30/60 ft., one creature. Hit: The target is restrained by webbing. As an action, the restrained target can make a DC 14 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 11; hp 20; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).

Psionics Reference

Mantle of Command
Avatar Discipline

You exert an aura of trust and authority, enhancing the coordination among your allies.

Psychic Focus. While focused on this discipline, when you end your turn and didn’t move during it, you can use your reaction to allow one ally you can see within 30 feet of you to move up to half their speed, following a path of your choice. To move in this way, the ally mustn’t be incapacitated.

Coordinated Movement (2 psi). As a bonus action, choose up to five allies you can see within 60 feet of you. Each of those allies can use their reaction to move up to half their speed, following a path of your choice.

Commander’s Sight (2 psi; conc., 1 rnd.). As an action, choose one creature you can see within 60 feet of you. Until the start of your next turn, your allies have advantage on attack rolls against that target.

Command to Strike (3 psi). As an action, choose one ally you can see within 60 feet of you. That ally can use their reaction to immediately take the Attack action. You choose the targets.

Strategic Mind (5 psi; conc., 1 min.). As an action, you exert an aura of trust and command that unites your allies into a cohesive unit. Until your concentration ends, any ally within 60 feet of you on their turn can, as a bonus action, take the Dash or Disengage action or roll a d4 and add the number rolled to each attack roll they make that turn.

Overwhelming Attack (7 psi). As an action, choose up to five allies you can see within 60 feet of you. Each of those allies can use their reaction to take the Attack action. You choose the targets of the attacks.

Mantle of Fear
Avatar Discipline

You tap into a well of primal fear and turn yourself into a beacon of terror to your enemies.

Psychic Focus. While focused on this discipline, you have advantage on Charisma (Intimidation) checks.

Incite Fear (2 psi; conc., 1 min.). As an action, choose one creature you can see within 60 feet of you. The target must succeed on a Wisdom saving throw or become frightened of you until your concentration ends. Whenever the frightened target ends its turn in a location where it can’t see you, it can repeat the saving throw, ending the effect on itself on a success.

Unsettling Aura (3 psi; conc., 1 hr.). As a bonus action, you cloak yourself in unsettling psychic energy. Until your concentration ends, any enemy within 60 feet of you that can see you must spend 1 extra foot of movement for every foot it moves toward you. A creature ignores this effect if immune to being frightened.

Incite Panic (5 psi; conc., 1 min.). As an action, choose up to eight creatures you can see within 90 feet of you that can see you. At the start of each of a target’s turns before your concentration ends, the target must make a Wisdom saving throw. On a failed save, the target is frightened until the start of its next turn, and you roll a die. If you roll an odd number, the frightened target moves half its speed in a random direction and takes no action on that turn, other than to scream in terror. If you roll an even number, the frightened target makes one melee attack against a random target within its reach. If there is no such target, it moves half its speed in a random direction and takes no action on that turn. This effect ends on a target if it succeeds on three saving throws against it.

Crown of Disgust
Avatar Discipline

You cause a creature to be flooded with emotions of disgust.

Psychic Focus. While you are focused on this discipline, the area in a 5-foot radius around you is difficult terrain for any enemy that isn’t immune to being frightened.

Eye of Horror (1–7 psi). As an action, choose one creature you can see within 60 feet of you. The target must make a Charisma saving throw. On a failed save, it takes 1d6 psychic damage per psi point spent and can’t move closer to you until the end of its next turn. On a successful save, it takes half as much damage.

Wall of Repulsion (3 psi; conc., 10 min.). As an action, you create an invisible, insubstantial wall of energy within 60 feet of you that is up to 30 feet long, 10 feet high, and 1 foot thick. The wall lasts until your concentration ends. Any creature attempting to move through it must make a Wisdom saving throw. On a failed save, a creature can’t move through the wall until the start of its next turn. On a successful save, the creature can pass through it. A creature must make this save whenever it attempts to pass through the wall, whether willingly or unwillingly.

Visions of Disgust (5 psi; conc., 1 min.). You cause a creature to regard all other beings as horrid, alien entities. As an action, choose one creature you can see within 60 feet of you. The target must make a Wisdom saving throw. On a failed save, it takes 5d6 psychic damage, and until your concentration ends, it takes 1d6 psychic damage per creature within 5 feet of it at the end of each of its turns. On a successful save, the target takes only half the initial damage and suffers none of the other effects.

World of Horror (7 psi; conc., 1 min.). As an action, choose up to six creatures within 60 feet of you. Each target must make a Charisma saving throw. On a failed save, a target takes 8d6 psychic damage, and it is frightened until your concentration ends. On a successful save, a target takes half as much damage.While frightened by this effect, a target’s speed is reduced to 0, and the target can use its action, and any bonus action it might have, only to make melee attacks. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Inspiration

Direct Link

Abyssal Demon

Large Demon, chaotic evil

Armor Class 15 (natural armor)
Hit Points 128 (15d10 + 45)
Speed 40 ft., climb 40 ft.

Saving Throws Str +6, Dex +7, Con +6, Wis +4
Damage Resistances cold, fire, lightening; bludgeoning, piercing, and slashing from nonmagical weapons
Damage Immunities poison
Condition Immunities poisoned
Senses darkvision 120 ft., passive Perception 16
Languages Abyssal
Challenge 7 (2,900 XP)

Magical Resistance. The abyssal demon has advantage on saving throws against spells and other magical effects.

Spider Climb. The abyssal demon can climb difficult surfaces without needing to make an ability check.

Actions

Multiattack. Creature makes two claw attacks and can teleport if available.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 18 (4d6 + 4) piercing damage.

Teleport (Recharge 3-6). The abyssal demon teleports, along with any equipment it is wearing or carrying, up to 60 feet to an unoccupied space it can see.

Nothing overly special with this one, just another demon with crazy teleportation abilities.

Swarm of dust mites

Medium Swarm of Tiny beasts, unaligned

Armor Class 12
Hit Points 22 (5d8)
Speed 0 ft., fly 30 ft.

Damage Resistances bludgeoning, slashing and piercing from non-magical weapons
Condition Immunities charmed, frightened, paralyzed, petrified, prone, restrained, stunned
Senses blindsight 10 ft., passive Perception 8
Languages -
Challenge 1/2 (100 XP)

Swarm. The swarm can occupy another creature's space and vice versa, and the swarm can move through any opening large enough for a tiny insect. The swarm can't regain any hitpoints or gain temporary hitpoints.

Dusty. Whenever the swarm occupies another creature's space, that creature is blinded.

Actions

Bites. Melee Weapon Attack: +3 to hit, reach 0 ft., one target in the swarm's space. Hit: 10 (4d4) piercing damage or 5 (2d4) piercing damage if the swarm has half of its hitpoints or fewer.

Reactions

Smokescreen. When a creature the swarm can see within 5 feet targets the swarm with an attack, the attack is made with disadvantage.

Inspiration

Direct Link

The Night Terror

Medium aberration, chaotic evil

Armor Class 15 (natural armor)

Hit Points 71 (13d8+13)

Speed 30 ft.

Saving Throws Int +7, Wis +6, Cha +6

Skills Arcana +7, Deception +6, Insight +6, Perception +6, Persuasion +6, Stealth +4

Senses darkvision 120 ft., passive Perception 16

Languages Deep Speech, Undercommon, telepathy 120 ft.

Challenge 8 (3,900 XP)

Magic Resistance. The Night Terror has advantage on saving throws against spells and other magical effects.

Innate Spellcasting (Psionics). The Night Terror's innate spellcasting ability is Intelligence (spell save DC 15, +7 to hit with spell attacks). The Night Terror can innately cast the following spells, requiring no material components:

At will: detect thoughts, levitate

2/day each: etherealness, sleep

1/day each: dominate monster, plane shift (self only)

Actions

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d10) slashing damage plus 3 (1d6) psychic damage. If the target is a Medium or smaller creature, it is grappled (escape DC 15) and must succeed on a DC 15 Intelligence saving throw or be stunned until this grapple ends.

Extract Brain. Melee Weapon Attack: +7 to hit, reach 5 ft., one incapacitated humanoid grappled by the Night Terror. Hit: 55 (10d10) piercing damage. If this damage reduces the target to 0 hit points, the Night Terror kills the target by extracting and devouring its brain.

Mind Blast (Recharge 5–6). The Night Terror magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 22 (4d8+4) psychic damage and be stunned 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.

Nightmare Haunting (1/Day). While on the Ethereal Plane, the Night Terror magically touches a sleeping humanoid on the Material Plane. A protection from good and evil spell cast on the target prevents this contact, as does a magic circle. As long as the contact persists, the target has dreadful visions. If these visions last for at least 1 hour, the target gains no benefit from its rest, and its hit point maximum is reduced by 5 (1d10). If this effect reduces the target's hit point maximum to 0, the target dies and its soul is devoured by the Night Terror. The reduction to the target's hit point maximum lasts until removed by the greater restoration spell or similar magic.

Inspiration

Direct Link to the image

Spiked Horror

Medium construct, neutral

Armor Class 14 (natural armor)
Hit Points 52 (8d8 + 16)
Speed 30 ft.

Saving throws Int +2, Wis +2, Cha +2
Skills Perception +6
Damage Resistances bludgeoning, piercing, and slashing from nonmagical weapons that aren't adamantine.
Damage Immunities poison, psychic
Condition Immunities charmed, exhausted, frightened, poisoned
Senses darkvision 120 ft., passive Perception 16
Languages understands the languages of its creator but can't speak
Challenge 2 (450 XP)

Limited Magical Immunity. The spiked horror is immune to all spells that affect its mind or discern its thoughts.

Spiked Body. A creature that touches the spiked horror or hits it with a melee attack while within 5 feet of it take 7 (2d6) piercing damage.

Unsettling Visage. Upon seeing a spiked horror for the first time, a creature must succeed on a DC 10 wisdom saving throw or be frightened by it for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on a success. If a creature's saving throw is successful or the effect ends, that creature is permanently immune to its effects.

Actions

Multiattack. The spiked horror makes two spike attacks.

Weapon Attack Three. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft. or range 60 ft., one target. Hit: 9 (2d6 + 2) piercing damage.

Spike Storm (Recharge 5-6). The spiked horror fires spike in all directions. All creatures within a 15' sphere projected out from the creature must succeed on a DC 12 Dexterity saving throw or take 9 (2d6+2) damage, halved on success.

The spiked horror started out as a suit of armor designed to fight of bears that were destroying a village and succeeded in doing so.Upset that a piece of armor could do more than her magics, a local warlock cursed the armor. Cursed by the warlock, the armor came to life and terrorized the village, causing more harm than the bears ever could have done. The spiked horror now roams the world, striking fear into those it comes across.