Mundane, Epic, and Legendary Monsters

The primary attribute that separates a monster from an animal is what has been named Ambient Magic. Generally speaking the more Ambient Magic a creature has the strong it will be. Most monsters gain Ambient Magic by eating other creatures with magic and by reproducing. Each generation is stronger than the last.
Mundane - Your standard monster. They have some Ambient Magic and their bodies can be processed into Magitek Oil.
Epic - A significantly stronger version of standard monsters. They are often bigger and meaner but tend to resemble their mundane counterparts. The Ambient Magic in their bodies usually pools in certain organs or body parts making them unique alchemical ingredients. Their bodies can also be processed in Magitek Oil but at a much higher efficiency.
Legendary - The most powerful type of monster. There are no general assumptions that can be made about them. The only thing that can be said about them for sure is almost all of the Ambient Magic in their bodies is concentrated in the core of their hearts. Eating the heart core can bestow permanent boons to those strong enough to kill a legendary creature. Eating the heart core causes the creature to turn to dust. Their bodies can be processed into Magitek Oil that has a purity of 100%, but very few people are willing to give up the heart core.