Mutations
Aquaris
AqrAqr / nAqr
Appearance
Aquaris causes fish-like scales anywhere on the body. The scales can be the color of the basecoat, or any other color including non-natural ones. Patterns on the scales 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.
On the Marean bloodline, aquaris can also (optionally) give the horse fish-like fins. This is exclusive to Marean only. Marean aquaris fins can have any color, and optionally also have patterns similar to tropical fish. The fin shape, size, and location is not restricted to the example shown below, you're welcome to draw your own.

Scales only
chestnut + aquaris

Scales can have any color
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.
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 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
Description

Placeholder
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, if the horns are growing out of a skeletal area on the horse then the horns can (optionally) be the same color as the Lich bones/markings, and same goes for the hooves.
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
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
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
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 scales on belly
chestnut + serpent

Wyrm bloodline with serpent scales on the tail
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