I'm sure there's a fancy and eloquent way to put it, but I'm not aware of what combination of words gets you there. I'm choosing to keep it simple.
I illustrated The Mirari Conjecture, a new Saga card coming out in Dominaria. I did it; I'm a Magic Artist; no takebacksies. Read on for the art description I worked off of and some close-ups of the goodness.
My most sincere thanks goes out to Kelly Digges and Mark Winters for the opportunity to be part of this amazing piece of Magic's history.
Color: Blue saga (see below)
TOPLINE: This is a new kind of spell called a Saga, which represents a particular moment in Dominaria’s past. Rather than a typical illustration, this piece represents an in-world artistic depiction of the historical event. Each Saga has its own unique visual conceit (e.g., stained glass, carved wood). All Sagas have an unusual vertical aspect ratio, with art running down the right half of the card. Unlike most other vertical-aspect Magic art, the entire image is clearly visible.
VISUAL CONCEIT: This “saga” is more of a diagram, created as a teaching aid by the mage-scholars of Tolaria.
BACKGROUND: The diagram depicts a magical disaster that the wizards of Tolaria only partially understand. A powerful artifact called the Mirari warped magic and biology across an entire continent, and the Tolarians are trying to figure out, based on field reports, where the Mirari was and what exactly it could do. Imagine trying to reverse-engineer a nuclear bomb from a fallout map—that, except they’re actually having some success with it, because they’re wizards.
ACTION: The primary element here is the MIRARI itself, toward the bottom of the image (see ref), but this is an abstracted “chalkboard” sketch of it. The shape of the base is probably simplified. There might be a cutaway view or some kind of chart or diagram drawn over part of it. As a substrate to the whole image is a MAP of the affected continent (see ref, though we don’t need to see all of it). The marked spots on the ref are “epicenters” of the Mirari’s influence. Those should be marked on the map, perhaps with other spots marked, less starkly, where magical “radiation” measurements were taken. Circles or rays might indicate zones of effect (again, like a fallout map).
Much of the content of the Saga is abstract—circles, whorls, lines connecting points, and “math” in an imaginary numeric system. We want this to look like something someone might realistically have drawn on a “chalkboard,” but it should also be pretty complicated—part of the point is that this object was very powerful, and the people analyzing it are very smart.