Snow Furies are a myriad group of savage ponies that can be found roaming the Northern Wastes. They appear in Fallout: Equestria - Rising Dawn.
Snow Furies are aggressive, extremely hostile ponies that attack anypony that isn't one of them on sight.
They lack any sort of conscience, reasoning, or logic, attacking, killing, and violating anything that crosses their paths. Snow Furies are infamous for their ambushes.
Furies are extremely resistant to pain and have little regard for their own lives in the pursuit of their mindless goals. This is evident in their resistance to the extreme cold, being able to burrow and wait underneath the snow for long periods of time to ambush an unsuspecting prey.
Along well traveled roads, snow furies bury themselves in the snow, erupting out of the ground to assault the unperceptive traveler. Sometimes, they single out groups of travelers, hunting them down to brutalize them, or to drag them beneath the drifts, never to be seen again.
Snow Furies often leave not a single trace of their victims. Those that survive their attacks describe the Furies dragging the crippled and dead away into the night; it is unknown what Furies do with their live victims, but it is believed that they do, in fact, consume the dead.
Snow furies are known to travel in groups, often large ones, combing the wasteland for victims to torture, kill, or force into blood sports for their entertainment.
It is unknown how ponies such as these come to be. Many Northerners believe that they are similar to the Southern wasteland's 'raiders'. Furies are remarkably difficult to observe, disappearing into the snow to evade capture or to retreat into what many believe are underground tunnels or burrows.
Survivors of close encounters describe the twitchy, demented behavior of these ponies, noting the dilating and constricting black veins or fibers in their sclera. Whether or not Snow Furies are victims of some psychosis inducing disease or magic is debatable.
Snow furies have been the subject of observation and analysis by Alicorns who refer to them as 'those touched by the madness.' Alicorns can detect a mentally debilitating, magical presence that is permeating the city, and find its presence stronger around snow furies, in particular. They refer to this presence as a darkness that limits their telepathic capabilities. This suggests that whatever created these ponies or turned them into the savages they are today is magical in origin.