Mutations
Aquaris
AqrAqr / nAqr
Appearance
Aquaris causes fish-like scales and/or fish-fins anywhere on the body. The scales and fins can be the color of the basecoat, or any other color including non-natural ones. Patterns on the scales and fins are allowed, as long as they resemble patterns commonly found on fish. The scales can cover the entire body, or just a part such as the neck or legs.
Only the Marean bloodline can have a true fish tail. Other bloodlines can have fins anywhere on the body, but the shape of their tail should remain true to their bloodline. Elwyn and Wyrm can have fins at the tip of their tails, replacing the tail-hair (if any is present, such as on Elwyn).

Scales only
chestnut + aquaris

Scales can have any color
chestnut + aquaris

Fins can be spined as long as the spines do not resemble horns, and look fish-like.
chestnut + aquaris

Fish-like fins
chestnut + aquaris

Marean bloodline with aquaris fins
chestnut + aquaris

Marean bloodline with aquaris fins and scales
chestnut + aquaris
Astral
AstAst / nAst
Appearance
Astral covers the horse in stars and galaxies, anywhere on the body and/or mane and tail. It can be any color and can optionally have subtle color shifts. Can go above or below white markings.
Astral only causes stars and small spots, it doesn't create moons or planets or other celestial bodies.
Astral can cause a starry "halo" effect, floating above or around them.

Astral halo effect
chestnut + astral

Astral galaxy
chestnut + astral

Astral star maps
chestnut + astral
Aurora
AurAur / nAur
Appearance
Aurora mimics the appearance of aurora borealis, in any color and anywhere on the body, including mane and tail.
Aurora can cause a "halo" effect, floating above or around them.
Just like in real aurora borealis, the markings can optionally move around and shift in color. It's entirely up to your preference if you want your character to have static or moving Aurora.
Aurora can be any saturated color, including colors not normally seen in aurora borealis, such as yellow or orange.

Aurora markings
chestnut + aurora

Aurora markings
chestnut + aurora

Aurora halo
chestnut + aurora

Aurora halo
chestnut + aurora
Optional effect: Bioluminescence
Aurora can optionally affect any Patterns by changing their color and letting them glow in the dark.

Aurora affecting papilio
chestnut + papilio + aurora
Eclipse
EclEcl / nEcl
Appearance
Eclipse causes glowing solar markings on or around the body. Any markings showing around the body is refered to as a halo.
Eclipse can optionally turn some or all white patterns black, and giving them a full or partial eclipse border with streaks and spots similar to sunrays. Eclipse can also create black areas on its own but then they need to be completely round/circular as seen on first example. Black areas created by eclipse can optionally affect mane/tail, whereas black areas caused by eclipse altering existing white markings must always affect mane/tail where it touches as seen on on the second example.
Eclipse can also optionally affect patterns, turning them black with an eclipsed outline, and can have the sunray appearance around the pattern. Can affect mane/tail depending on if the pattern does.
Eclipse should not create a starry effect. While some stray spots are allowed the overall appearance should resemble rays of light.
Eclipse should always be in the color range of orange/yellow. Can only be other colors if shimmer is present (restricted to the available colors of shimmer present).
Eclipse can optionally affect horns and/or hooves, turning them completely black regardless of other genes present, and giving them a glowing or sunray outline. Eclipsed horns/hooves is not allowed to show colors of elemental alignments, shimmer, or any other gene that can affect horns/hooves.

Eclipse on chestnut with no other genes present
chestnut + eclipse

Eclipsed splash
chestnut + splash + eclipse

Eclipse with sun rays only
chestnut + eclipse

Eclipse halo
chestnut + eclipse

Eclipse halo
chestnut + eclipse

Eclipsed overo (some white unaffected but still has sun rays) with halo
chestnut + overo + eclipse

Eclipsed pard with halo
chestnut + pard + eclipse

Eclipsed horns

Can optionally cause the eyes to have black sclera.
Flora
FlrFlr / nFlr
Appearance
Flora causes flowers and plants to flourish on the horse, either as if they're growing on the body or as markings on the coat anywhere on the body.
Any kind of plants, flowers, mushrooms, or natural growth is allowed, including fruits and berries.
The flora can optionally be affected by seasons, for example leaves turning yellow in the autumn or flowers blooming during spring and summer, different seasonal plants growing during different parts of the year, or it can stay the same all year round.
Flora can optionally affect horns and hooves to make them look like wood.

Flora markings on the coat
chestnut + flora

Flora growing anywhere on the body
chestnut + flora

Flora can optionally affect horns and hooves
Lich
LchLch / nLch
Appearance
Lich causes a skeletal appearance, either as a bone-like armor covering the horse or a decayed appearance revealing the bones within.
Lich can also simply appear as skeletal markings on the coat.
Bones and markings can be as realistic or stylized as you want, you can combine it with other mutations e.g. flora+lich to get a "Día de Muertos"-inspired design.
Lich can optionally affect horns and hooves to make them look more bone-like, and the horns and hooves can be the same color as the Lich bones/markings.
Lich bones and markings can be any natural color (shades between or including white, brown, grey, and black, as well as darker/lighter than the coat). Lich can only be unnatural colors if it is either affected by the Elemental alignment of the character, or if Shimmer is present, in both cases restricted to the available color palette of the element or shimmer variation.

Lich with bone-like armor
chestnut + lich

Decayed/skeletal lich
chestnut + lich

Lich imitating natural white markings
chestnut + lich

Lich markings, affected by ember shimmer
chestnut + lich + ember shimmer

Lich can optionally affect horns and hooves

Can optionally cause the eyes to be fully white or fully black
Opal
OplOpl / nOpl
Appearance
Opal has multiple effects that can be included in the design either separately, or combined. The Opal mutation can cause gems or crystals anywhere on the body, of any type of gemstone. The gems can be polished or natural-shaped.
Opal can also cause an iridescent sheen through the coat, giving the design a nacreous appearance. This should not change the color of the design, it will just give it a pearly shine on top.
Opal is also able to affect horns and hooves, turning them gem-like or crystalline, in any color.

Gemstones
chestnut + opal

Pearly sheen on the coat
chestnut + opal

Opal can optionally affect horns and hooves
Opulent
OtOt / nOt
Appearance
Opulent acts as a modifier on other genes, altering patterns, white patterns, and other mutations to give them a golden or metallic color and sheen. Opulent can also optionally cause a freckled effect through the coat and small streaks in the mane and tail. Opulent can affect horns and hooves, turning them into a shiny metal.
Opulent doesn't have to fully affect a pattern, it can also cause golden accents such as filling or outlining the pattern. It can co-exist with other mutations, for example with lich it may turn the bones gold, on serpent it can cause the scales to be golden or have a golden rim.
Affects mane and tail if the pattern/marking it's altering does.
Opulent should always be either gold, silver, bronze or copper, and should generally have a metallic highlight or sheen. Variations are also allowed, such as white gold or rose gold.

Opulent freckles
chestnut + opulent

Opulent leopard appaloosa with unaffected white markings
chestnut + leopard appaloosa + opulent

Opulent opal causing golden gemstones and a golden sheen through the coat
chestnut + opal + opulent

Opulent pard
chestnut + pard + opulent

Opulent roan in a rosy gold tone
chestnut + roan + opulent

Opulent tabby in a silver tone
chestnut + tabby + opulent

Tabby with opulent accents
chestnut + tabby + opulent

Opulent horns
Plumage
PlmPlm / nPlm
Appearance
Plumage causes feathers anywhere on the body, it can give the horse a fully or partially feather-covered body like a bird and add decorative feathers in mane and tail or replace the mane entirely with a feathered crest. Plumage can not cause a complete bird-tail, that is a tail type limited to the Alcyone bloodline. Plumage can also not cause a Veilhorn to have wings on its own, but it can alter the appearance of Seraph wings.
Plumage feathers can be any color, and can have patterns resembling those on bird feathers. If the Seraph mutation is also present and has a feathered wing type, the Plumage mutation can optionally affect those feathers as well, by altering colors/patterns and/or adding decorative feathers.
On Alcyone, the plumage mutation can alter the color and patterns of the feathered tail, and can also add longer trailing or decorative feathers.

Crested and feather-covered neck, with shoulder and tail plumes
chestnut + plumage

Crested plumage neck
chestnut + plumage

Plumage can add decorative/trailing feathers and alter the color of seraph wing feathers
chestnut + plumage + seraph

Alcyone bloodline with plumage affecting tail color
chestnut + plumage
Primal
PriPri / nPri
Appearance
Primal has multiple effects that can be included in the design either separately, or combined.
Primal will always be in the color of your characters Elemental alignment. This means if your character has the Fire elemental alignment, the Primal mutation can only be in the color range available to the Fire palette.
Primal can create soft gradients anywhere on the body, mane, and tail. These must always be blended softly into the base coat, and can only have "sharp"/straight edges if the occlusion trait is present to partially "cut off" and hide Primal. Subtle dapples are allowed. Mane and tail may never be fully colored, it should always be a partial gradient - the mane/tail base color should be visible either at the tips or at the roots of the hair. The same goes for the body, it may never be fully colored by Primal.
Primal can fully or partially affect the color of any present Patterns, by changing the pattern into the color of the elemental alignment. This can optionally affect mane/tail, if the pattern does.
Primal on the body, mane, and tail must always appear beneath white markings, whether it is applied as a gradient or affects an existing pattern. It may not alter white markings or skin color. Primal cannot create patterns or textures on its own and may only affect color.
Primal on the horns and hooves may optionally create element-inspired patterns. This can go above or below white markings (your choice). Primal may never alter the shape or physical texture of the horns, it should only create element patterns such as swirls, stripes, or other patterns inspired by the Elemental alignment.
For clarity: Element-inspired patterns or textures are only permitted on the horns and hooves. On the body, mane, and tail, Primal is strictly color-only and may not create patterns or textures - it can only create soft gradients and affect the color of present Patterns.

Arcane primal on chestnut, doesn't affect skin color
chestnut + primal

Arcane primal on chestnut splash (subtle dapples), always goes below white
chestnut + primal + splash

Light primal on chestnut
chestnut + primal

Shadow primal on chestnut
chestnut + primal

Air primal on chestnut pard
chestnut + primal + pard

Water primal on chestnut shroud
chestnut + primal + shroud

Fire primal on chestnut tabby
chestnut + primal + tabby

Nature primal on chestnut tabby (accents only)
chestnut + primal + tabby

Nature primal on chestnut tabby splash, affecting mane/tail, and always goes below white markings
chestnut + primal + tabby + splash

Primal can optionally cause horn/hoof patterns. From left to right showing shadow, fire, and water element.
Seraph
SphSph / nSph
Appearance
Veilhorns with the seraph mutation will have 1 or more sets of wings. The wings will generally either be those of a bird or bat, but other variations such as fairy-like are also possible.
Seraph can be combined with other mutations to alter the wing appearance, for example the Serpent mutation can make the wings scaled and spiked like a dragon, Astral mutation can make the wings starry and lustrous, Flora can make the wings appear like leaves or petals, Lich can make the wings skeletal, and so on.
The color and patterns of seraph wings should match the colors/markings/mutations on the rest of the horse, they cannot be a completely new random color.
Feathered seraph wings may have different colors and patterns if the plumage mutation is also present because plumage can affect the colors of feathers.

Bat-like seraph wings
chestnut + seraph

Feathered seraph wings
chestnut + seraph

Fairy-like seraph wings
chestnut + seraph

Scaled seraph wings with serpent mutation
chestnut + seraph + serpent

Starry feathered wings with astral mutation
chestnut + seraph + astral
Serpent
SptSpt / nSpt
Appearance
Serpent causes armored dragon-like scales anywhere on the horse, and can range anywhere from covering the entire body to just a small part.
If the scales cover the topline such as the neck, back, or tail they can also optionally cause typical dragon spines/spikes.
On bloodlines with long tails (Elwyn and Wyrm) the serpent mutation can optionally cause a spiked or arrow-like tip similar to a dragon's tail tip. This can replace tail hair, if wanted.
The scales can be any color, both natural and unnatural. Scales can show the colors and patterns of any present genes.
Serpent can optionally cause webbed spikes, similar to dragon-like fins.
Serpent can also cause elongated reptile mouths, which may also cause them to have sharp teeth that may or may not be visible even when their mouth is closed.

Serpent scales on belly
chestnut + serpent

Wyrm bloodline with serpent scales on the tail
chestnut + serpent

Can have webbed spikes similar to aquaris fins as long as it's not fish-like fins.
chestnut + serpent

Can cause elongated mouth with or without teeth/fangs sticking out.
chestnut + serpent
Wulf
WfWf / nWf
Appearance
Wulf causes extended mane growth anywhere on the body. The long fur can either be the same color as the mane and tail (for example, a bay can have black fur even if it's on a part that would normally be brown), or the same color as the underlying coat.
Wulf can also optionally cause fangs or canine teeth.

Spine and elbow fur
chestnut + wulf

Fully covered neck
chestnut + wulf