Created by the Supreme Divine that preceded Miral in her final act (she was grasping for straws because she feared death and was seriously delusional. Even Archangel Peter agreed that it was bad at the time) as ruler to exterminate the demon race. This wasn't an official declaration of war, but Miral ordered the attack soon after his Ascension and the declaration followed at that point. She tried to funnel them down into LowGround through the Fulcroi rift, but ended up failing and the vast majority of them remained on MidGround. Only those that could fly/glide down survived the fall through the rifts.
Why the Fulcroi rift? So the beasts could work their way to the central city without instantly being killed off by the Legions. It both was to give the monsters time to grow in number and to pick off any chances of reinforcement. Because of this location, the population was worse on Fulcroi than Delune-Vitar, also hence why there are a couple arenas on Fulcroi. As for Bhormenn, due to the Great Trees, the lightbeasts couldn't make it far inland before being picked off by the wild dragon population.
On Delune-Vitar, naturally, they were drawn to chaos and panic, so they especially loved the war border and wherever the divines broke through and raided towns.
They were most famously known for being used in fights at the infamous gladiator ring in Volie (on Fulcroi). The handlers would starve them days before a fight to make them ten times more determined to devour its prey in the ring.
Currently, they have evolved with the life of the land over several hundred years, which in turn created monsters no longer purely of lightbeast genetics. Some of these lightbeast descendants have been known to gain some intelligence, especially those with skills of mimicry.
Common features before outbreeding:
-Extremely reckless, no thought process (the equivalent of the phrase 'no thoughts, head empty')
-White colored
-Possible chance of pastel accents
-Pitch black eyes
-Skeleton with a skin painted over it, possible long fur to hide the extreme frailness
-Despite lack of muscle, extremely powerful when it actually lands a good hit
-Either sharp spikes, claws/talons, fangs, or multiple of the listed
-Head must be crushed/speared or the 'primary eye' has to be stabbed through in order for it to be killed
After outbreeding:
-As stated previously, they got smarter, some more than others
-Coloring and features vary between subtypes
-Depending on the species, they have more muscle on them rather than just bones
-The elimination method requirement fazed out through the early generations and hasn't returned, balancing out the fact that they're less of a glass canon and have a stronger sense of survival