Hell Hag

The appearance of a Hell Hag is a mightily inauspicious event, as it represents the fusion of three hags into a singular entity of tremendous evil and power. Precisely how this occurs is unknown, Hell Hags are notoriously difficult to talk to, and regular hags refuse to speak of hell hags or how they are created. It is good way to end up in the hag's cooking pot, or have your eyes melted out of your skull by means of a powerful curse.

Appearance

The Hell Hag has three 'forms' or general appearances, and it moves between these three forms as it sees fit.

Maiden - in this form, the Hell Hag appears as an attractive woman of the most common race in it's vicinity, be it human, goblin, or something else. In this form, it can be charismatic and charming, both in mimicking the general behavior of an attractive young woman, and in using manipulative magics to control its potential victims. Maiden form is commonly used for scouting settlements, misdirecting potential heroes, and interacting with non-hags without raising suspicion. The maiden is also a hunter, and will seduce young foolish men that strike its fancy and will take them to secluded places to paralyze and eat them, preferably keeping them alive as long as possible. Some hell hags develop a taste preference, and this can be used to start tracking one, should its tastes become known.

Mother - The Hell Hag increases in size from medium to large creature, and it's three heads are manifested, and is resembles a three headed female giant, though it's appearance attribute plummets. This form most resembles a death giant, or similar large humanoid associated with filth and death. The Hell Hag uses this form to become a mother of monsters, and will consume different creatures, and then produce a horrific egg sac like a shark or skate. Left in brackish water, the pulsating life energy inside matures and eventually hatches into a hybrid abomination, created from life and death magic. 

Hag Spawn constitute the most common servants of Hell Hags, and some retain the dim memories and a shadow of the skills they had in life, before being devoured by the hag. 

- a hairless/rugose purple skinned version of a normal animal, increased one to two size categories, improved armor, vicious predatory intelligence.

- a humanoid hag spawn will retain memories of the last victim the hag ate, fragmentary, but still. Their alignment becomes chaotic evil, and anyone they knew in their previous life will become a preferred target.

- A human/animal hybrid will have a horrific combination of both creatures, with the most recently consumed creature providing most of the creature. A Hell Hag who consumed a cougar and then a female archer would create a humanoid (genderless) with feline attributes and the muscle memory of an archer, and confused broken memories of the woman she once was.

- Magic users create hag spawn that have a single innate spell like ability, appearing as withered and diminutive imp like creatures. Hell Hags will keep these as magic slaves, and if running low on mana/magic power, they will eat them like living potions. 

Crone - The most powerful form of a hell hag, the crone appears as a giant three headed hag, with horrific sagging features, rope like muscles, and creating an aura of dread around itself. In this form, all three hag heads can speak, the hag sprouts extra arms, and can cast multiple spells as a time, one for each head, and the heads can shift spells between themselves so that one can cast, then another can concentrate and maintain a spell while the main head continues its plans. The three heads work together and there is no hostility or tension between them. The Crone has all the powers of three hags combined into the body of a powerful and damage resistant giant.

The horror of the crone hell hag is that it is large enough and strong enough to pick up human sized foe, subject them to a rending attack intended to dislocate or even rip limbs off. While in this position, it is not uncommon for a hell hag to bite the head, face, or throat out of a foe and throw their crippled body or corpse to the ground before moving to the next target. 

Crone Hell Hags are powerful magic users, and are not as powerful as liches, but more common. 

Creation

A Hell Hag is created when a coven of hags succumbs to starvation and rather than becoming dormant or burying themselves in the swamp until greener times come, the strongest hag overpowers and consumes her two hag sisters. The lone hag will abandon its former nest and then conceal itself for a long period of time. Eventually it will seemingly perish, and then it's skin will bloat, and stretch, until it rips apart and the newly born hell hag crawls out of it's horrific incubator. Once born, the Hell Hag will consume the carcass of the last hag it was born from, and then begin it's new life as a horrific super predator.

The species of the final hag will provide most of the visual details of the hell hag, most of whom were born from nightmare hags (purple skinned) devouring their covens. It is less common for a lesser hag to accomplish this, but covens made entirely of one type are not uncommon. The spell lists and magic aptitudes of a hell hag are most strongly influenced by its hag form. A green hell hag will favor green hag magics, for example. 

Normal Hags consider a hell hag to be an abomination, and while they would love to destroy it, they are generally smart enough to know that if one hag was able to overcome and devour two other hags, and then survive into a hell hag, facing down a lone hag is a suicidal plan. Even regular hag covens will relocate rather than face a hell hag. The Hell Hag only has to take out one of the coven members, devour it, and escape. The coven is greatly weakened, and the hell hag will go hatching out a hag hag spawn. The worst outcome is the hell hag devouring the whole coven and then crapping out a massive egg sac and spawning an entirely new hell hag daughter to itself.

Hell Hags specifically hunt their own kind for this reason.

Usage

The Hell Hag is a high power monstrous foe that should motivate the party of heroes to do their utmost best to face and destroy this monstrous foe. It is predatory, remorseless, and relentless. It could serve as an apex villain for a large portion of a campaign, and do so without the often predictable surrender and join the heroes trope that is popular in shonen anime over the last decade. 

Hell Hags are big, flashy, and when it comes to facing one, they bring the pain. Physical attacks should be big and brutal. Body breaking throws, using large objects like trees or even the group fighter as a melee weapon, removing limbs, heads, or hands with a snarling bite. Magic likewise is big and bad, with two back up heads, a hag can throw down like a hoe down, while its other heads are casting buffing magic on itself, summoning horrors, and raining damage magic down on the PCs. 

Hag Spawn let them create minions who are much easier to fight than the hell hag itself, but also creates the threat of former allies being eaten and shat out as egg sacs that will hatch into hagspawn versions of themselves with a passion for killing and eating their old friends and family. Likewise, the PCs could see this same fate themselves.