Expanded concept and class based on the final entry of this table.
You are not a person. You look like a human, or a fantasy race of your choice, but you are not. Spells, magic items, and potions that have specific effects on that race or type of being do not effect you; you are treated as something “else”. Though you are similar and blend in with their society, you have a tell- roll this table. Use the left entry if your highest stat is even, use the right if its odd.
“Other” Tell Table - 1d12
 You have a six fingers / You have a claw on your big toe
 You have a spiked, puncturing tooth behind your incisors / You have too many teeth
 You smile too wide / Your mouth is very small
 Your eyes are heterochromic / You have a second iris + pupil under your eyelid
 You shiver in hot places / You sweat in cold places
 The hairs on your back react to touch / the hairs on your chest are strong as nails
 You have a hare lip / All your scars are symmetrical along your body's vertical axis
 Your blood is bright pink / You don't bleed; your wounds sound like gas escaping your veins
 Your veins have a blackish tint / Your sweat is similar to honey
 You're double jointed in both your elbows / Your spine is very flexible, like a ferret's
 Mimic the chirp of a songbird when happy / Mimic a horse's whinny when frightened
 Stick out your tongue; taste things at distance / You can and enjoy eating rotten foods
At 1st, 3rd, and 5th level, you gain +1 to hit with all weapons and Fearsome Flesh.
Every even level, you get +1 to rolls to tinker with machines, magitech devices, and power crystal arrays. If this involves creating portals between dimensions; you get a bonus +1 to the roll.
You have power slots. At 2nd, 6th, and 10th level, you gain a slot. These slots have two purposes. The first is to force any mutation or curse you acquire to become beneficial, or gain a beneficial use. This mutation also becomes a part of your body permanently, 'locking' it in place, so only a powerful magic ability that could take away a natural ability can remove it. If the mutation was neutral and provided both good and bad effects, you can incorporate it into your biology to minimize its negatives and improve its positives. Vestigial limbs and organs gain a use, excesses and growths grant bonus hit points, cursed luck is redirected upon opponents and so on. If you don't have any mutations, you can keep a slot open until you get a good one or roll on a random power table.
The second use of the power slots is for your special power; Fearsome Flesh. You can only use this ability once per adventure per power slot. Make an attack- on a hit, you deal (1d6 + maximum power slots) whatever damage type you want. Your body shifts and morphs to perform the attack. You cough up liquid nitrogen bile to freeze an enemy, or a spiked tentacle shoots from your gut to pierce an enemy's armor, and so on. Using this power makes all hirelings following you take a morale check, as it is quite frightening to see your boss as an inuman monster. Additionally, whenever you use up all of your Fearsome Flesh uses on a single adventure, you gain another permanent tell to mark you as an Other.
Similar to the undead, you can be turned. If you are successful Turned, you disappear from the world for 1d4 days. You have to find the “back door” to get back in. When you return, you return with a Terrible Knowledge from your time away. If you are turned and the result is a Destroyed, you return after 1d4 seasons with your highest stat permanently reduced by -1d6 and your level drained by 1, but with another Terrible Knowledge in tow and an obedient 1 HD Null Beast as a familiar.
Your condition is genetic and is passed on to your children. The older you get, the more inhuman you become, your tell is further exaggerated and your body morphs into your adult form. Eventually, you'll be unable to fit in with human society on your own.
At 10th Level, you have become a Outsider and can no longer be turned by a Cleric. Only very powerful magic can banish you now. Your family clusters around you further; you gain 3d6+1 loyal cultists, one of whom is always a 3rd level magic user and 1d4 of your family members develop into 2 HD Null Soldiers. If these soldiers are killed, 1d4 family members will step up to transform to help protect your brood. Also 2d6 Null Beasts bud off of random family members asexually, which will still be treated as children. If you are killed you will return in 2d6 years as long as your family continues to call to you for you to return to them; the cult requires 1d8x100 gold each season to operate. Any mutations you have gained along your adventures can now be hidden in your body with a slight tell, similar to your "Other" tell, but can be drawn out at a moment's notice.
Additionally; you may now build Gateways. Gateways are circles of standing stones, marked arches in city squares and cathedrals, quiet corners in libraries, and within holes dug between the house's own floorboards. You can pass through the gateway to spend 1d3 days acquiring another Forbidden Knowledge OR you can use a Gateway to instantly travel to any other Gateway you've made. Gateways must be sustained once per season through either constant guarding and suspicious activities by your brood, or bribes to locals costing 1d6x50 coins for a Gateway, or a sacrifice of a pure virgin for one Gateway. Failing to sustain a Gateway will make it permanently lose its powers.
Morale- 4, unless commanded to attack
Null Beasts appear as small animals like cats, dogs, chickens, ferrets, rabbits, unusually big rats or lizards, as well as birds like crows and pigeons. While appearing as these animals, they do not fit in with animals of the same type, which are spooked and will break their necks in a panic to escape the false null beast. Null beasts are very cowardly on their own without direction, in which case they will fight to the death or as long as they are commanded. When they die, Null Beasts have a 50% chance to revive in 1d6 exploration turns after being killed at 1 hit point and severely weakened- to slink off and lick their wounds.
Null Beasts have a body that can reform in ways to make attacks. New teeth and claws sprout from unusual places, legs bend wrong to jump up to bite your face, and so on. They don't seem to feel pain, and can eat anything biological regardless of the form they appear. These animals act as familiars, guards, and pets of the “Others”.
Null Soldier (2 HD, +3 to hit, -2 AC, 2 frenzied flesh at 1d6+1, reassembly)
Null soliders look like normal people or beings of specific races, tied to their brood. However, they are truly not and have off proportions and usually have either a calm smile or their teeth are constantly gnashing their lips and cheeks. Null Soldiers have no survival instinct, and seem unsure on how to use their bodies; they move unnaturally and fast, and their attacks allow them to exploit their unnatural biology.
When Null soldiers attacks, every part of their body contorts and mutates to cause injury. They may break their own teeth with their inhumanly strong bite, then using their tongue like a piston to spit the shards at you as a gun blast up close. Their eyes may pop just to shoot acid on your face when you wrestle them to the ground, their arms and joints bend backwards and bone exits skin to act as stabbing and slashing weapons, new mouths or organs may just appear from within them.
If the Null Soldier is killed by an elemental attack (burnt to a crisp, frozen solid, zapped by lightning, or melted by acid) or is totally crushed or exploded apart by a very strong attack, they will simply die like they're supposed to. But if they are killed by traditional weapons; the Null Solider will reassemble into a new lesser form with 1 HD and 1 attack. The Null Form is made of whatever is left over of the damaged and slain soldier, bending into a new form to bite and gnash. A decapitated head sprouts spider legs to jump and bite; a disemboweled soldier has his intestines slither out and calcify whatever unnatural organs were within into clubs. It cannot reassemble twice.