 set of noxious and evil creatures from material darkness that have the capacity for destruction, disease, and death. Angremenu and his evil creatures attack Ahura Mazda's material creations once they have been created. And then that is why we have a battleground between good and evil forces on earth. So this is where the dualistic elements come in as well. The reason I mentioned this creation story is because it gives meaning to why mankind and Zoroastrianism is said to have free will.