Marvelous Magical Mutations

"The powers of biology and thaumaturgy mock both pitiful attempts at breeding and the pathetic will of nature. Today, we march forward, to conquer the farthest horizon, and bring into being a new breed of creature - one that is utterly faultless, free from the strictures of evolution and deific design. The kingdom shall behold and cower before my grandest creation: myself! Pull the lever, Kraj!" - Archbiomancer Phynch Darloss, seconds before metamorphosing into a hideous hybrid of elf, crocodile and crab.

by Bram Sels

Mutant: Reroll a stat from your base folk and keep higher, then reroll a stat at random and keep lower. Instead of your folk's abilities, roll 1 mutation from the Cosmetic/Positive tables, and 1 mutation from the Mixed/Negative tables.

d20 Mutant Origins:
1. A bastard wizard did it.
2. Abducted and experimented on.
3. Actually an alien, apparently.
4. Ancient magical artifact catastrophe.
5. Bitten by a radioactive animal.
6. Cursed by a vengeful priest.
7. Drank from a really, really gross lake.
8. Grew up in irradiated hellhole.
9. Healing magic gave you a little extra.
10. Infected by mutation plague.
11. Lost a game against the fey.
12. Meteor crashed nearby.
13. Narrowly survived death, mutations saved you.
14. Next phase in evolution showed up early.
15. Parents were mutants, belong to proud mutant family line.
16. Powerful magical creature as an ancestor, hit really weird puberty.
17. Survivor of magical weapon attack.
18. The Octarine Star shone upon your birth.
19. Used self as test subject.
20. Wanted power, at any cost.

by John Ariosa

Mutations 
(largely inspired by/curated from Coins & Scrolls' list)

d20 Cosmetic
1. Animal Ears. d6: 1. cat, 2. dog, 3. lizard, 4. rat, 5. bat, 6. bug antennae.
2. Ant Blood. Your blood is now ants. Your skin crawls.
3. Bizarre Colour. Your skin is patterned with two colours (d8: 1. Red, 2. Orange, 3. Yellow, 4. Green, 5. Blue, 6. Indigo, 7. Violet, 8. Octarine).
4. Compound Eyes. Whole bunch of little eyeballs, like a raspberry.
5. Deadened. You look like a rotting corpse, as if you'd been dead for a week.
6. Detachable Tail. Newt-like. Falls off when you take a Wound, regrows.
7. Dopplered. You red-shift and blue-shift at walking speed, and leave a blurred trail behind you.
8. Engorged. d6: 1. Arm, 2. Leg, 3. Head, 4. Torso, 5. Hands, 6. Feet.
9. Extra Fingers. d4 per hand.
10. Extra Mouths. Gain d6 extra mouths across your body.
11. Faceless. All your senses work as normal, but your face is smooth and featureless. Don't ask how you eat/speak, you just do.
12. Flora. Grow leaves and flowers instead of body/head/facial hair.
13. Gemstone Eyes. Like cut (1d6: 1. rubies, 2. sapphires, 3. pearls, 4. diamonds, 5. obsidian, 6. bismuth). Actual gems, worth 10gp each.
14. Goat Horns. Small and pointy.
15. Hole. Mysterious hole right through your torso.
16. Skeleton Limb. One of your limbs becomes a skeleton of itself. Works normally.
17. Third Eye. On your forehead.
18. Transparent Skin. Everyone can see your organs.
19. Unusual Genitals. Whatever you had going on down there is different and weird now.
20. Vestigial Wings. d6: 1. Bird, 2. Bat, 3. Dragon, 4. Butterfly, 5. Beetle, 6. Elemental. Cannot fly.

d20 Positive
1. 1000 Eyes. They cover your body. You cannot be Surprised.
2. Amoebic. You can split and reform yourself. Each half has half stats, half HP, and half the abilities on your sheet.
3. Caustic Spray. New pulsing glands on back. Can fire 20' cone, 2d6 acid damage, smells awful.
4. Dragonbreath Gland. 30' cone, 1d6 fire damage, once per day.
5. Fractal Fingers. One hand only. Cannot drop objects held in that hand, and advantage on DEX tests with that hand. 2d1000 fingers.
6. Frog Tongue. As a whip.
7. Gills. You can breathe underwater.
8. Glow Pockets. Can glow (as a candle) at will.
9. Goat Legs. 2 of your legs become goat legs. You are not slowed by broken or rocky terrain.
10. Hydra. If head or limb cut off, CON save. If passed, 2 new heads or limbs emerge.
11. Leathery Hide. +2 AC.
12. Magnetic Sense. Lump of metal protrudes from head. Can detect magnetic north unless near a strong magnetic field or iron.
13. Out of Phase. Flickery. You can hover through solid objects by taking 1d6 necrotic damage per round.
14. Perfect Memory. Can INT test to recall incredibly trivial details. Brain glows through head.
15. Prehensile Tail. Can grip items, advantage on climbing.
16. Scorpion Tail. +1 attack per round dealing 1d4 poison damage.
17. Shark Teeth. Whole mouth full of them. 1d6 bite damage.
18. Spider Gland. On both wrists. You can spin 10' of rope per day.
19. Spores. Grow glowing, bulbous lumps. 1/day, coat a 30' radius in purple hallucinogenic spores.
20. Venomous. Your natural attacks (bite, claw, etc.) deal an extra 1d4 necrotic damage if they break the skin.

d20 Mixed
1. Antlers. Ridiculously large. d6 bludgeoning damage attack, but can't fit through doorways or thin passages.
2. Boneless. You can squeeze through gaps as small as your head. -1d6 STR.
3. Cascading Mutations. Whenever you're Wounded, gain a random (d100) mutation until you heal.
4. Claws. Your fingers fuse into sharp claws. You cannot hold weapons. You claws do slashing damage, step up unarmed damage die.
5. Crab Arm. One hand becomes a claw. 1d8 bludgeoning damage, can't wield items.
6. Crab Legs. They replace your normal legs. Can scuttle sideways at normal speed.
7. Detachable Limbs. Your arms, legs, and head can be removed and reattached.
8. Duplication. Split in half. Reduce all your Stats by 1d6 and your HP by half. Your "twin" rolls new stats and HP. 3-in-6 of your twin being comically evil.
9. Echolocation. You echolocate within 30', as a high-pitched audible whine. Can't turn it off.
10. Extra Limb. d6: 1. Left arm, 2. Right arm, 3. Left leg, 4. Right leg, 5. Tentacle, 6. Roll again, but you get d4 more.
11. Face Mimic. When you kill someone, your face shifts to look like theirs.
12. Ink Cloud. When startled, WIS save. On failure, spray ink in a 20' radius.
13. Ink Skin. You can cause words to appear on your skin by concentrating. Your thoughts also appear there; CHA save to resist this.
14. Iron Spines. You're covered in 6" iron spikes that protrude from your bones at odd angles. Can't wear armor, but deal d6 piercing damage to anyone who hits you in melee.
15. Lamarckian Evolution. One hand turns into a terrible version of the last tool you used.
16. Metal Skin. Your skin is covered in metal plates. You cannot swim or wear armour, and -1d6 Dexterity. +8 AC.
17. Molten Blood. Your blood is now molten iron. You are incredibly warm and deal 1d6 fire damage to anyone who wounds you in melee. 4 Inventory Slots are filled with Iron Blood.
18. Pheromones. Attracts insects, 20' radius.
19. Polymorphed. Reroll your race.
20. Universally Compatible. If it's alive, you can reproduce with it.

d20 Negative
1. Atrophy. One your limbs becomes withered and unusable. If leg, halve move speed. If arm, -1d6 STR.
2. Borrowed Time. Everyone around you is perpetually uneasy. At the end of each session, make a random ability score save vs. death. Pass three of these saves in a row and death gives up; heal this mutation.
3. Brittle-boned. Always wounded by bludgeoning damage.
4. Combat Fever. Perpetual barely-constrained anger. Can only restore HP if you've fought today.
5. Creaking Joints. Go last in initiative order. Mundane tasks take twice as long.
6. Cyclopean Eye. No depth perception, disadvantage on ranged attacks.
7. Delicious. You smell absolutely delicious and are going to be the first target in combat.
8. Dietary Shift. Save every time you eat a ration or vomit profusely and take 1 damage, unless that ration is (d6: 1. Blood, 2. Metal, 3. Wriggling, 4. Sunlight, 5. Poisonous, 6. Magic)
9. Flaky. You're water-soluble. 1 necrotic damage per round in rain, dissolve if submerged.
10. Ichorblood. You perpetually leak a sticky, flammable, black ichor from your pores and orifices. Whenever you take damage, take an extra point of necrotic damage.
11. Independent Hair. Your hair can move on its own, and takes as much effort to cut as hacking off your own limb. It likes messing with you.
12. Metal Reactivity. You break out in painful welts (1 slashing damage/round) whenever you touch metal.
13. No Skin. -1 AC, leave trail of blood on everything you touch.
14. Overheating. After performing strenuous activity (physical or mental), CON save vs. d6 fire damage. You're constantly steaming.
15. Parasite Friends. They live in your guts. Need to eat 1 extra Ration per day, or take -1 STR and -1 CON. Recover 1 point of this stat drain for each day you meet the parasites' needs.
16. Pox-ridden. You've got an incredibly degenerative disease. Whenever you would roll an HD to regain HP, do so with disadvantage.
17. Sudden Rapid Disassembly Syndrome. When surprised, save vs. a limb falling off. You can reattach them, but it takes a round of holding it there while it seals back on.
18. Tumorous Growths. All over your hands and face. -1d6 DEX and CHA.
19. Unstable. Guts glow a menacing orange. When you take a Wound, CON save vs. exploding. 3d6 firearm damage, 20' radius.
20. Xenobiology. Your organs are arranged oddly and perform the wrong functions. Randomly reassign your ability scores whenever you level up.

d20 Supernatural
1. Animating Touch. Objects you touch animate as a 1HD Animate Object. You can only have one object animated this way (changes when you touch something new), and it won't follow your orders.
2. Aurovore. You can eat 5gp instead of a ration, and can digest metal.
3. Blood Foam. When you bleed, it expands into a soft foam that rapidly hardens into a brittle shell. 1ft^3 per hit point of blood.
4. Chronologically Detached. Slightly transparent. Take 1d6 time damage to disappear and reappear that many hours in the future. Takes that many minutes to phase out.
5. Colour Ripple. You are always the colour of the thing you are looking at.
6. Eldritch Markings. Skin covered in colored marks; reflect your personality and deeds.
7. Elemental Affinity. Your attacks also deal (d6: 1. Acid, 2. Cold, 3. Fire, 4. Lightning, 5. Psychic, 6. Necrotic) damage, but when you're hit you also take that type of damage. Your element crackles around your hands and face.
8. Emergency Teleport. Jitter constantly. If you are reduced to 0 HP, you teleport 2d10x10' in a random direction.
9. Flame Hair. Hair is literally fire. Doesn't burn you, sheds light as torch if you feed it a ration.
10. Foggy. The air around you condenses into a fluffy, obscuring cloud.
11. Hovering. 1" off the ground at all times.
12. Mercury Arm. Arm replaced with liquid metal. Can squeeze through gaps.
13. Mimic. Bird beak replaces your tongue. You can mimic all voices, music, and natural sounds.
14. Nominative Imperative. You know whenever anyone says your name.
15. Open Soul. Visible, roiling aura. Magical effects always have the maximum (sum) on you.
16. Personal Gravitational Field. Small objects (pebble-sized or smaller) orbit you.
17. Phenotypic Mirror. You take on the appearance of the first person you see each day (don't gain their stats).
18. Second Sight. Always staring into the middle distance. Can see ghosts, spells, and spirits as faint outlines.
19. Unnoticeability. If you're not being actively looked for, you won't be perceived until you make an unexpected noise or interacting with someone.
20. Wyrdsight. One eye has glowing cataract, can see souls. Migraines and disadvantage on WIS and CHA tests when open/uncovered.