Luminants

Luminants, an arcane creature native to Harokin, went extinct during the Shattering due to lack of the environmental arcana that they required to live. Most arcane animals on Harokin were killed off or starved out similarly, but luminants were one of the few that did not also have surviving populations on Lumasca or the newly-renamed Shattered Isles.
Luminants were warm-blooded creatures the general size and shape of deer, though they possessed many similarities to thin-bodied sighthounds and bore pelts of feathers, marking them as chimeryx in nature. Their delicate, almost-humanoid faces bore a singular, small horn in the middle of their forehead and were framed in a ruff or mane of downy feathers. Luminant feathers were a useful resource for animals and kinvari alike, being constantly molted and replaced throughout the seasons, and--as their name suggests--bore a faint, ethereal glow. Spring-time feathers were rosy pink, summertime feathers were honey-gold, autumn feathers were warm orange, and winter feathers were an icy blue-silver.
Luminants were primarily herbivores, browsing on berries, fruits, roots, and nuts, but were known to occasionally scavenge from abandoned kills or eat eggs when a nest was located. They were social creatures, living in small family herds of less than a dozen individuals; a matriarch would lead a few attendant males along with her sisters and daughters. The matriarch seemed to be chosen based on her arcane robustness, rather than combat prowess, but few kinvari ever witnessed a new female uprooting an existing matriarch through any means.
Tall and slender with long necks, luminants were gazelle-like in silhouette but for their eerily kinvaren faces and their long, peacock-esque tails. These long-feathered tails could not display quite in the same half-circle as a true peacock, but they could be lifted upwards like a standing banner and used for signaling herdmates or confronting a would-be aggressor. Luminants were not particularly easy prey for most hunters, be they beast or kinvar, but as arcane creatures they possessed a goodly volume of mana in their bodies, and so predatory arcane creatures often targeted them for an infusion of mana into their own diets.