From the introduction:
These new brands of magic exist exclusively in the True World, and their power is great. New spells are being developed every day, while others are simply being rediscovered.
Pluma taps into the hidden power of feather magic and Hishna that of talons, claws, teeth and venom; yet they are two sides of the same coin.
Welcome to the magic of the True World; be sure to use its power wisely!