Lycanthrope

Lycanthropy is a curse that transforms and mutates the victims body into a bestial creature when specific conditions are met. The curse is agitated by certain energies, which causes the transformation into the bestial form. The most common occurrence is when the full moon is visible and capable of radiating a tremendous amount of energy.
Lycanthropy, while most often found as werewolves, is an incredibly diverse affliction whose range of bestial form can be seen in canine, ursine, lupine, vulpine, feline, and countless others. But a common trait shared between all of these, is that the curse provides an expedited regeneration factor, likely to account for the rapid changes in the physical body when transformation occurs.