Any advice on this process that doesn't sum up to "Do what you want."?

Most things come down to this in writing...

Anyway, I would look at the character's philosophy of life and how they approach things. Like, okay, a "sliver-walker" or a "walker-who-likes-slivers" might, in your mind, need access to all five colors of magic in order to summon each and every sliver the game has ever made. Fine. But what's that 'walker like? What does that 'walker care about? Why is that 'walker so obsessed with slivers? Is it because he loves the strong sense of community that the sliver's natural link provides? If so, maybe he is mono- (or primarily) . Is the character a researcher who became exceedingly knowledgeable on slivers to the point where she could control them? Maybe she's . Does the 'walker believe that slivers are an inherently apex race, or could be the most efficient path to power and domination? .

With character creation, it's probably more important to look at personality and motivation than actual spellcraft. Take Lukas Harran, for instance. DavFlameRock made him a character who, due to circumstances, can only use mana. Now, admittedly, my writing of him may have him appearing a bit more than Dav likely intended, but that's my fault, not his. The point is, the colors of mana used in a character's magic does not necessarily HAVE to match the colors that identify that character.

Raven's thoughts are all good ones. The one comment I would add on top of that is to suggest this exercise.

Imagine that you're giving me an elevator pitch for your character. In other words, you have 15-20 seconds to explain your character to me. That forces you to focus in on the things which really define your character.

For example, my elevator pitch for Beryl might be something like: "She's a talented enchantress with a powerful but unpredictably flair for pyromancy who is haunted by fear and self-doubt over a terrible mistake she made as a young child." I think that character reads very to me.

Now Beryl also has some aspects of her personality and spellcraft which have a flavor. But those are minor facets of her, and not the sort of things I'd mention in 15-20 seconds. So I don't really think of as part of her color identity.

You may find that something along these lines helps you to zero-in on the most important colors.

Cool, I'll try that! Unfortunately it seems it would only work on a character that has been figured out in every way other than color focus. When I think about it, whether it's top-down or bottom-up, as far as my planeswalker characters (found in my signature) go, only 2 were conceived with their personal information in mind before their abilities or magical associations. Those being the black-green "guardian/slayer" and Woolsey, the White-Black loxodon. So that definitely triggers the "limitation breeds creativity" where I give them magical affiliation stemming from these colors and their preferences, not the other way around.

Well, here's a question for you. If we're going with the sliver walker, why do you want a sliver walker? What do you hope to accomplish with that character?

When starting from what type of magic the character uses (cryomancy or auramancy or lithomancy or whatever), after deciding on their overall field of study, think about how they use their magic. What do they do with it, and what is the feel of their use? For example, when making a lithomancer: are they crafting stone into complex shapes for architecture and tools and weapons? Gazing into stones to scry the shape and nature of the land? Enchanting stones to have special magical properties? Turning them into spellbombs? How does it feel when they sit down to work their magic? Do they go about it through a mystical union with their materials, by flinging their emotions and desires at it, by carefully measuring ingredients and chanting magic words, by channeling their faith or praying to a higher power? As you get a feel for these things, they can guide you more towards some colors over others.

Hm? The sliver walker was just an example. The walker is much closer to an actual concept I would hope to build on.

Not to limit you excessively, but I do want you to know that we already have a walker in the archives. He doesn't have a dossier though.

And correct me if I'm wrong, Barinellos, but isn't he sort of exclusively Snow? Like, he is no color?

Yeah, like my thought process with that ogre walker that I posted yesterday was... well, actually it was "it'd be really cool to make a half-orc druid with the beast transformation ability in 5e, and they could be genderqueer, and it could get into all these ideas about transformation and identity and body modding and stuff!" and then I decided I wanted to play a Tiefling Trickster Cleric instead and thaaaat's why zie became an M:EM character.

But basically, while I started out looking at the skillset in the 5e PHB, I took that idea and thought: "What can I say thematically with this ability? What does this power allow me to show or explore or express that I couldn't in another setting/with another power?"

For my tiefling that I'm playing, I decided the trickster-domain cleric ability that allows characters to create an illusory duplicate of themselves allowed the character to express a literal duality in his identity--his faith in Corellon vs the diabolical call of his blood.

For what eventually became the ogre, I decided the ability to transform into beasts allowed me to explore fluidity in identity and the historical association between queerness and monstrosity, and the way transformation can outwardly project an inner emotional world.

From there, it's pretty obvious what colors fit best with those ideas, I think. The tiefling, in Magic, would probably be RWB, and the ogre is RG. It's the abilities but also an aesthetic and a theme.

And also a personality should probably be in there somewhere but as I've mentioned before I have a harder time getting characters to a point where they come alive in my head, unlike most writers I think.

Snow is a color!...
But no, he is exclusively snow. It isn't just that he's a cryomancer, he is an actual walker.

Oh, then nevermind on some things, I didn't know you could just label a character as and be done with it. That doesn't really sound right.

As far as a planeswalker goes, my incarnation of the concept would either be an elf (snow elf because for a time my headcanon for Kaldheim was that it was a hodgepodge of different planes, resulting in a very very Skyrim-esque world) or perhaps a sentient elemental.

The only characters I have that I have yet to break them into any certain color(s) due to something like that are the Frostmage currently in question, an oldwalker "mythmage" (if exemplified by a deck type, he would be a Child of Alara deck with cards chronicling the Shards block, Maze's End deck with maze runners, some sort of Elspeth+Ajani focused Theros deck, etc) I may or may not intend to relate him or her with the "Wizard's Tower", full of spells and history of other planes (presumably Blue at least)

and a half-elf half-kor Totem Armor druid/shaman I have so far decided was fine to be Green-White since there's only 3 Blue cards with totem armor and there is just one dual-color card that is specifically those 2 colors. (also deciding that it would have elf and kor heritage might have solidified it)

Surely Aerik gets his magic from.... lands. Which almost always produce colored mana. And casts spells that require colored mana even if it is snow mana.