Still working on Dark Sun stuff. Here’s some of the mutations available to characters:

At character creation you may have as many mutations as you like, or none at all. Each time you take a mutation, you must roll for increasingly more deformities on Table 1C: Deformities. Your first mutation gives you one deformity, your second gives you two more, your third gives you three more, and so on.

More arms! Add one arm to your number of arms. This can be taken multiple times.
Memetic hole! People have a hard time remembering you. You start with no contacts, and anyone separated from you for at least 5 minutes will need to make a DC 15 Intelligence check to remember who you are or forget everything they know about you.
Eyeful! Your face is covered in eyes. Any effect that would blind you must effect you twice to do so. This can be taken multiple times, increasing the number of times the effect needs to hit you.
Tough skin! Whether it’s patches of chitin, scales, tumorous callouses, living stone/crystal, protrusions of bone, etc., you have resistance to a weapon damage type of your choice. This can be taken multiple times.
Claws! Whether it’s feline claws, insectoid, reptilian, etc., you have claws that you are proficient with and deal 1d6 slashing.
Weird size! You are one size category smaller or larger than your species would dictate.
Psychic talent! You learn one new psychic talent. This can be taken multiple times.
Pouches! You have hidden folds and pockets in your body where you can hide objects or creatures no larger than two size categories smaller than you. It takes a DC 25 Investigate check to find an item hidden this way.
Wings! In place of arms you have feathered wings with three-fingered hands on them. You can glide as part of your movement, but always end on the ground or falling.
Detachable parts! As a free action you can cause a body part of your choice to fall off. This does no damage to you, and the body part regrows in a week.
Swarm! You are a mound of many much smaller things. You can send a chunk of your body up to 100 feet away and perceive through it, though you cannot take actions through it other than movement. Any damage they take is dealt to you as psychic damage.
Fast! Your base speed increases by 10 feet. This can be taken multiple times, giving you five fewer feet each time (minimum 1).
Arachnoid! You have the lower body and lower limbs of a spider, and four compound eyes. Your climb speed is equal to your base movement, and you can spin webs as though casting the Web spell at 2nd level. Your web ability consumes one day’s worth of food and water from your body each time it is used.
Vampire! If you are grappling or restraining a creature, as an action you may absorb 1d6 HP from the creature. This counts as necrotic damage.
Jelly! Your body is flexible. You can squeeze through any space your head can fit through, and you have advantage on checks made to escape a grapple.
Shapeshifter! You can change the appearance of your face as an action. To mimic a specific person, make a Charisma (disguise kit) check as usual.
Cantrip! You learn a cantrip. This can be taken multiple times.
Matter eater! You can consume anything that fits in your mouth, though when using this ability you do not gain any sustenance from it as the consumed item is destroyed utterly, gone from this world. If it is poisoned, diseased, radioactive, molten hot, freezing cold, etc., it does no damage to you. If you consume a magic, psionic, or living thing with this ability, you must immediately make a death saving throw. On failure, you pop out of existence, dead forever. On success, you drop to 0 HP with two death save failures.

d20, Feature
1, Huge tumorous growths cover your body. An ability score drops to 7 if it’s above 7. Roll 1d6 to determine which one.
2, Purely aesthetic deformity.
3, You are hideous, physically and empathically. You give off a psychic aura of repulsion and distaste. All Charisma-based rolls you make are at disadvantage.
4, Purely aesthetic deformity.
5, You are hairless and your skin is totally translucent (just your skin, not your insides). Your max HP is reduced by 15.
6, Purely aesthetic deformity.
7, Your eyes are bulging, glassy, and totally white. You require twice the normal amount of rest.
8, Purely aesthetic deformity.
9, You are constantly sweating a bitter, non-nutritious, dark oil that smells acrid. You require twice the normal amount of food and drink.
10, Purely aesthetic deformity.
11, Your tongue, teeth, and lower jaw are missing, and you are permanently mute.
12, Purely aesthetic deformity.
13, You are missing a leg. Your speed is halved.
14, Purely aesthetic deformity.
15, Your heartbeat is as loud as a beating drum and can be heard from quite a distance.
16, Purely aesthetic deformity.
17, Your eye sockets are empty, and you are permanently blind.
18, You have no ears and are permanently deaf.
19, Your skin is cracked, crispy, and burnt. You take 1 fire damage every hour you spend in the sun.
20, You are missing an arm.