Alistair

Unlike normal deer peryton's do not shed their antlers, instead they keep growing larger and more intricate as each year passes. The larger the antlers, the more light they carry, and as such they're considered to be the best guides.

Equally unlike deer, a peryton's antlers are made of hollow bone (like that of a bird) allowing them to be lightweight despite their size -- in fact their lights often weigh more than their actual antlers. This does make them rather useless in terms of defending themselves, as do the lanterns they carry, though typically Peryton use magical means of avoiding detection for both itself and the being its guiding making defense unnecessary. Most sightings of them are considered will-o-wisps, as the only thing un-concealable is their lights.

That isn't to say, of course, that all peryton's are equally skilled with magic. It takes years of practice to master and many lack the patience required to hone their skills before attempting the daunting tasks involved with becoming a prestigious guide; those who try too soon, without the ability to hide themselves, are often faced with the blasphemous act of taking a life to protect the lives of themselves and the being whom they're guiding. If forced to take a life, a Peryton will gain a shadow it would otherwise lack; resulting in them being unable to manifest their own light and thus losing their ability to guide anyone, including themselves.

Perytons that cast a shadow are usually avoided at all cost; by their un-shadowed brethren as well as other beings. It's quite common for those with shadow to turn malicious, savage, and sometimes even cannibalistic; believing that consuming one with light will dissolve their shadow and restore their ability to create lights.