Monster of the Week: Drahies

Take a Harpy, combine it with the corrupting effects of an elder Black Dragon for long enough, and you'll get the Drahies, horribly mutated Harpies, under the loose influence of the dragon, with only one goal: inflicting pain onto anything alive...
Add onto that some almost unique, once in a generation, mutation and you get my first attempt at making a "Stuff of Legend" creature, the crazy Tainted Drahie, probably totally unbalanced, but a pretty sure bet for a TPK...

"Wait..they do WHAT?" (a player, as the GM explains what happens to his male PC after being captured by a Drahie flock)

Drahie
Medium Flying Humanoid
Armor Class 14 (15 w/ shield)
Hit Points 20 (3d10+3)

Speed 30' land (6 squares) / 50' flying

Initiative +2

Senses normal (60')
STR(12/1) DEX (14/2) CON(12/1)
INT(10/0) WIS(14/2) CHA(10/0)
Alignment Chaotic evil

Languages Draconic

Traits

• Pleasuring Pain: Every-time a Drahie is injured in any way, it gains d6+1 temporary HP until the beginning of it's next turn. This can happen only once in-between the Drahie's turns

Actions

• Melee Attack - Barbed Stab: +3 to hit (reach 5', one creature). Hit: 4 (d6+1) piercing damage. On hit, the target makes a DC10 CON saves. On failure, it takes another d4 damage from the barbs of the spear. ("the Drahie tries to stab you with it's barbed spear!")
• Range Attack - Barbed Netting: +3 to hit (range 50', cube 5'). Hit: Each Large or smaller creature within 5' of where the net lands must succeed a DC12 DEX save or be Restrained by the net. A creature can break free of the net by using it's action to make a DC12 STR check or by dealing 10 slashing damage to the net (AC 10). Each attempt to break free of the net causes d4 damage to the creature.
• Range Attack - Acid Spit (4-6): +3 to hit (range 30', one creature). Hit: 6 (2d4+2) acid damage.("the Drahie spits a black acidic substance at you!")

Encounter Building Level (3) Experience (90)
Description

Once, long ago, Drahies were Harpies like any other. Then an elder and powerful Black Dragon arrived in the area and began corrupting the land and it's inhabitants. Centuries later, the Harpies began to change, generations after generations. Their women features became scaly and deformed, their angel like arm-wings mutating into horrible bat-like black wings, with sharp talons.
Now, under the influence of the dragon whether it's still here or not, the Drahies live for only one thing: Pain, and the pleasure it offers. Their entire society is based on a terrible sadomasochist idea that leaves their children covered with scares and the adults half crazed.
When the Drahies capture another humanoid male to reproduce, the mating process is a combination of pain, pleasure and torture, driving the target mad after a couple days and usually disfigured by the acid secretion of the Drahies.
Drahies are usually under the domination of an elder Drahie, usually one who evolved with magical powers of some sort (see Tainted Drahie below). All under her are considered Daughters  and she is the Mother, all powerful, until a younger one kills her.
Drahies can, under very rare circumstances, be reasoned with, usually when under threat of total destruction. Such dealings are however made with the Mother, the Daughters only seeking immediate pleasures, nothing else.
Once every 3-4 years (d6+1), the entire tribe of Drahies will go out on the hunt for about a month to capture male humanoids with which they can reproduce, this is called a Harvest. Such flocks can lay waste to entire villages, sometimes up to 100 miles away from their lair.
Environment(very rare/5-10)

Caves near swamps when an elder Black Dragon resided for a long time. Sometimes, the clans migrate but only to another swamp area.
Behavior 
Sadomasochist, Matriarchal, Predator (active hunter), Territorial, Demented

Load-Out 
Barbed spears, Barbed nets (see notes). Sometimes carry shields as well as armor parts.
Treasure

Often carries metallic crafts in their hair or as piercings and pendants with gemstones and the like. Has no use for coins whatsoever, though it'll probably be with whatever remains of the males they captured, left behind in their lair as trophies and home decorations after they are...done with them.

"Investigate the lair they said, piece of cake they said, the Black Dragon hasn't been seen for decades they said...That's it, I'm retiring!" (Randrag, lone survivor of a Tainted Drahie encounter in the Swamp of Eternal Darkness)

Tainted Drahie
Medium Flying Humanoid
(Stuff of Legends)
Armor Class 15 (16 w/ shield)
Hit Points 88 (8d10+8)

Speed 30' land (6 squares) / 80' flying

Initiative +2

Senses ultra-vision (60')
STR(18/4) DEX (14/2) CON(16/3)
INT(18/4) WIS(14/2) CHA(14/2)
Alignment Chaotic evil

Languages Draconic

Traits

• Pleasuring Pain: Every-time a Tainted Drahie is injured in any way, it gains d10+2 temporary HP until the beginning of it's next turn. This can happen only once in-between the Tainted Drahie's turns
• Spell-casting - Innate Powers (3-6): The following are considered Natural Abilities, with a +6 Magic Ability level, 1 Action casting time, no components required and used as level 5 spells slots. After using an Innate Power, at the beginning of it's following turns, roll a d6. On a result of 3 to 6, the Tainted Drahie regains the use of it's Innate Powers:
• Blight, Confusion, Dispel Magic, Evard's Black Tentacle, Feeblemind, Hold Person, Inflict Wounds, Suggestion, Stoneskin, True Seeing.
• Spell-casting - Rituals: The following are considered Natural Abilities Rituals, with a +6 Magic Ability level, 5 minutes preparation (Trance), no components required and used as level 5 spell slots. The Tainted Drahie can use any number of these per day, as long as it concentrates for the required time.
• Invisibility, Disguise Self, Scrying, Speak with the Dead, Commune (only with Black Dragons within a 100 miles radius, if any).
• Spell-casting - Cantrips: The following are considered Natural Abilities Cantrips, with a +6 Magic Ability level, Swift Casting, no components required and used as level 3 spell slots.
• Cause Fear, Command, Comprehend Languages, Detect Magic, Ray of Enfeeblement, Ray of Frost, Read Magic.
• Stuff of Legend - Resistances: The Tainted Drahie has Advantage to all it's Saving Throws.
• Stuff of Legend - Extra Reactions: Tainted Drahies are among the stuff of legend, and as such, nature, destiny or superior powers allow them to take extra Actions. At the beginning of each of it's turn, the Tainted Drahie gains 2 (d4) Extra Reactions, which can be used at any time, as normal Reactions. Unused Reactions gained this way are lost when the Tainted Drahie begins it's next turn. These Reactions must be among the following list:
• Any Attack Action: As listed in Actions.
• Disengage: As per rule but only 5' (1 square).
• Extra Opportunity Attacks Reactions: As per rule.
• Stuff of Legend - Momentous Presence (Aura, 100'): Simply being in the presence of a Stuff of Legend creature can shake even the mightiest of warriors. Any enemy Creature beginning it's turn within 100' of a Tainted Drahie must succeed in a CHA contest versus the Tainted Drahie. On failure, the creature suffers the following effects until the beginning of it's next turn:
• Disadvantage to all Actions, Skill Checks and Saves.
• Concentration effects suffer Severe Distraction with a DC equal to the current CHA score of the Tainted Drahie (as per rule).
• Spells cast are considered as having Longer Casting Time for this turn and as if immediately hit by damage equal to the Tainted Drahie current CHA score (14 CHA by default, giving a DC 7 CON(save), as per rule), no matter the actual casting time of the spell. (note: no damage is actually taken by the creature casting the spell when this effect triggers)

Actions
(When taking an Attack Action, the Tainted Drahie can make another Attack as part of that Action)

• Melee Attack - Barbed Stab: +5 to hit (reach 5', one creature). Hit: 6 (d6+4) piercing damage. On hit, the target makes a DC10 CON saves. On failure, it takes another d4 damage from the barbs of the spear. ("the Tainted Drahie tries to stab you with it's barbed spear!")
• Range Attack - Barbed Netting: +5 to hit (range 50', cube 5'). Hit: Each Large or smaller creature within 5' of where the net lands must succeed a DC12 DEX save or be Restrained by the net. A creature can break free of the net by using it's action to make a DC12 STR check or by dealing 10 slashing damage to the net (AC 10). Each attempt to break free of the net causes d4 damage to the creature.
• Range Attack - Acid Spit (5-6): +5 to hit (range 60', one creature). Hit: 12 (2d10+2) acid damage.("the Tainted Drahie spits a black acidic substance at you!")

Encounter Building Level (8) Experience (2000)
Stuff of Legends, use with care and purpose.
Description

Sometimes, maybe once in a generation, one of the baby Drahie will be a unique mutation in itself, an incarnation of the corruption of the Black Dragon. Such Drahie, even among the tribe, is known as the Tainted and is often revered, like a prophet, for it's appearance, as much as for the power she will develop once adult.
While normal Drahies can still be somewhat remembered as Harpies, Tainted Drahies cannot, their female forms almost completely corrupted, their entire skin covered with a thick layer of dark scales, their face a mix of humanoid and reptilian form, and a long powerful tail completing the mutation. Stronger, more intelligent and above all, able to use raw innate magic abilities, the Tainted Drahies will become the Mother of the clan once adult, and a reign of terror and suffering will often dawn soon after in the entire region around the lair.
Most of the time, Tainted Drahies will remain in their lair, lost in a perpetual trance state, between pleasure and pain, as the Daughters toy with her skin, planting hooks, feeding her, protecting her. During the harvesting season, she will however lead the flock and keep the best males to herself, killing any of the Daughters who dare oppose her.
In battle, the Tainted Drahie will use her flying abilities to keep out of harm's way, unleashing her most devastating abilities as soon as possible in a "shock'n awe" attitude, to force her preys to immediately submit. She will also order her Daughters around, even to their death if need be. 
If beaten, she will try to retreat then will spend her ENTIRE time plotting and enacting her revenge. This may last for years, even decades, potentially forcing her to stalk the culprit to distant lands, even interact with civilizations (using Disguise Self to hide her nature) or sacrificing her entire flock for this goal. Nothing else will matter, until she dies or has her vengeance...which probably involves a lot of pain for a very long time. Her target may even evolve to become some kind of unique mate, her desire for vengeance transforming into an odd love/hate demented relationship.
Environment(stuff of legends/1)

Caves near swamps when an elder Black Dragon resided for a long time. Sometimes, the clans migrate but only to another swamp area. It's almost unheard of to have more than one Tainted Drahie in a clan, since any adult Tainted Drahie will simply kill other newly born Tainted Drahies.
Behavior 
Sadomasochist, Matriarchal, Predator (active hunter), Territorial, Demented, Intelligent Schemer, Monomaniacal

Load-Out 
Barbed spears, Barbed nets (see notes). Sometimes carry shields as well as armor parts.
Treasure

The body of the Tainted Drahies is usually covered in metallic piercings, spikes and hooks, keeping her in a constant state of pain and pleasure. They also sometimes wear the cut faces or more intimate parts of their most recent males victims on their breasts. Yea, that kind of stuff. Doesn't say Demented in their behavior for nothing...

Note Barbed Spear (Melee Weapon, Simple, Exotic)
Damage: d6
Weight: 5lb
Properties:

• Thrown (range 20/60)
• Versatile (d8)
• Barbed: On hit, target must succeed a DC10 CON save or suffer an extra d4 damage.

Simple, Exotic: Requires training and Simple Weapon Proficiency.

During each long rest, the PC can declare training with the Barbed Spear. If so, have the PC do a DC10 DEX/INT (his choice) check. After 5 successes, the PC can use the Barbed Spear as a normal Simple Weapon. Critical Successes count as 2 successes. Critical Failures remove 1 success.

Note Barbed Net (Ranged Weapon, Martial, Exotic)
Damage: n/a
Weight: 4lb
Properties:

• Thrown (range 20/60)
• Each Large or smaller creature within 5' of where the net lands must succeed a DC12 DEX save or be Restrained by the net. A creature can break free of the net by using it's action to make a DC12 STR check or by dealing 10 slashing damage to the net (AC 10).
• Barbed: Each attempt to break free of the net causes d4 damage to the creature, whether the creature succeeds or not.

Martial, Exotic: Requires training and Martial Weapon Proficiency.

During each long rest, the PC can declare training with the Barbed Net. If so, have the PC do a DC10 DEX/INT (his choice) check. After 5 successes, the PC can use the Barbed Net as a normal Martial Weapon. Critical Successes count as 2 successes. Critical Failures remove 1 success.

Quick Plot Hook
As the PCs approach a village, a flock of Drahies arrives for their Harvest, grabbing many of the male villagers away, including their local contact! As the flock leaves with it's cargo after a brief fight, a group of family members approaches the PCs, offering various personal belongings and services for the safe return of their loved ones.
There starts a race against time: Find the lair of the Drahies in the local swamp and rescue as many of the men as possible, before they are driven insane under torture, or die after playing their part...
...That, and avoid pissing off the elder Black Dragon, in deep slumber under the putrid waters of the swamp for the past couple centuries...