Fey Evolution Merchant

In the blue sky and white clouds, the dawnlight star bird spreads its wings and flies. On the vast grasslands, the swift cloud leopard rushes forward to hunt. In the mottled rainforest, the acid-eating giant python hides among the tree shadows. Under the deep blue sea, the white-crested mosasaur stirs up waves.

Lin Yuan discovers that he can make spirit beasts evolve without limit, continuously purifying their bloodlines.

Dust butterfly -> steel butterfly -> jade butterfly -> beryl imperial butterfly

This is a pure pet novel, a world of beast tamers.