The Edenian murder cat is a magically engineered species of feline who act as instant assassins for the fae and for others who can conjure the requisite spell. Once transformed from its original species into an honest-to-goodness catus mortiferum, the individual will hunt their creator’s desired target until the target is dead or the cat itself has been killed.
Though a murder cat may be created from any feline species, the domestic cat and the African lion are the preferred starting points—the house kitty for its ability to blend in and kill on the sly, and the lion for its brute force.
Perhaps the most striking thing about the murder cat, however, is that it continuously evolves over the course of its life—a result of the enchantment which created the species. It develops new limbs, senses, and other mutations whenever they might help it better do its job. And with each creature it kills, the murder cat takes on any genetic attributes from its victim which might be advantageous during its next assignment. This leads to some rather monstrous-looking individuals, including the murder cats which inspired the Earthling legends of the manticore.
And though most murder cats are created by magic users, they are also capable of reproduction—either with others of their kind, or even occasionally with mates from their original species (provided they have not evolved to the point of becoming genetically incompatible).