Free Marks
Free marks consist solely of Lightening and Darkening. They can make the areas colored in the shown regions in the following image either lighter than, or darker than, the base coat. These areas are the inner ears, around the eyes, the front of the lips, and the flesh.
While you can adjust the shades (value) of the base coat in these areas, you can't hue shift more than 5% on your program's Hue slider. However, you can lighten all the way up to white, or darken all the way to near-black, so long as the lines remain visible. This means you can't use 0% value black!
Nuances & Shading
Nuance coloring/shading is not allowed for Kijis or Tallies. Additionally, you may not shade or shine the main bodies (unless you have the Shiny body trait, which only allows shine and not shadows), but you may add subtle shading and shining to the claws, hooves, and teeth. For metallic traits, like Golden and Silver bones, you may do more drastic shading and shine.
Bones
Bones includes the hard (or certain keratinous) parts of the body such as claws, hooves, teeth, horns, and any body or back spikes. These can be colored a natural bone-like color (white or yellowed off-white, but not so yellow to appear "rotten" or being mistaken for Golden Bones, and not dark brown or black since those require Black Bones), the same color as the base coat, or slightly lighter or darker than the base coat, assuming they aren't being affected by a mutation (such as Golden Bones, Silver Bones, Black Bones, Painted Claws, Glowing Bones) or Keratin Energy.
Markings that can Affect Claws/Hooves Color
The following is a list of markings that can affect the color of the claws or hooves. While claws and hooves must follow the color rules as the rest of the bones for the most part, if any of the markings listed below are present, the claws/hooves can match the color of the said marking (Or be slightly lighter or darker).
These markings are modifiers and only affect the claws/hooves if affecting one of the markings in the next section:
Inverted
Filter
Bi-Colored
Ombre
Some of these markings can affect the claws/bones partially, while others would affect them all.
Dunked - Can affect the whole of the claws/hooves
Boots - Can affect the whole of the claws/hooves
Dipped - Can affect the whole of the claws/hooves
Highlight - Can affect the whole of the claws/hooves
Shadow - Can affect the whole of the claws/hooves
Tips - Can affect the part of the claws/hooves it touches
Toasted - Can affect the whole of the claws/hooves
Pinto - Can affect the part of the claws/hooves it touches
Skew - Can affect the part of the claws/hooves it touches
Tabby - Can affect the part of the claws/hooves it touches
Faded - Can affect part of the claws/hooves
Panda - Can affect the whole of the claws/hooves
Orca - Can affect the whole of the claws/hooves
Stained - Can affect the whole of the claws/hooves
Dark Side of the Moon - Must affect part of the claws/hooves
Good and Bad Wolves - Must affect part of the claws/hooves
Please also note that Golden and Silver Bones requires the claws/hooves and teeth to be gold or silver respectively, while what Black Bones colors is entirely optional, so long as at least one needed area is blackened.
Painted Claws/Hooves has to cover the full range of the claws/hooves, while every other bone area is optional.
Glowing Bones is treated like Black Bones in that it has to affect at least one area, but unlike Black Bones which can allow a piebald effect, Glowing Bones has to affect an entire area.
Please see the guides on each of the aforementioned mutations for more information!
Flesh
Flesh includes the paw pads, mouth, and nose, and the small triangle of flesh in the corner of the eye, but NOT the inner ears. Flesh can be any natural color such as pinks, reds, chow blue or slightly purplish, or brown. Natural blacks are fine for the nose so long as the lineart can still be discerned. Flesh can also be the same color as the base coat, or slightly lighter or darker. You may have different colors in different ranges; for example the nose can be black, the paw pads can be pink, and the mouth sections (tongue, membrane, gums) can be varying shades of pinkish red.
Any other colors desired will require Energy Soul.
Halos
By default, halos around the character are not allowed. You may not do a sticker halo, a glow halo, or a shadow halo, even if it's extremely thin or subtle. This is because there are traits and charms that add halos to a character, and adding any kind of colored outline will mimic these, which will create an illegal design if your spirit lacks the necessary trait(s).
Any of the following may add a halo to the character:
Energy Soul, mimicking the other energy colors on the character and creating a fullbody glow effect. (Energy Trail may interact with this to create a trailing type of halo.)
Light Charm, creating a very light-colored or white halo.
Dark Charm, creating a very dark or near-black halo.
Starry Aura, creating a starry/galactic effect on a dark backdrop as a halo.
Gleaming Body, creating sunrays and a halo effect around the body.
Coloring Lineart
Coloring the lines is allowed, but the lines need to remain darker than any surrounding color. To get this effect, you may use layer filters in your program, but be careful not to make the lines so faint that they're practically invisible at a glance. You may not make very light or white lineart without having the Heavenly Body trait. Additionally, your lineart can't be a noticeably different color than the surrounding colors; for example if your character is blue, you can't make the lines yellow, unless the lines are being affected by Energy.