Unrealistic towns in Heroes of Might and Magic V.

Did the Necromancers create the world? And can they control the moon, the earth, and the soul?

To understand, you need to read the history of Ashan. They worship the goddess Ascha - the mother spider, the dark aspect of the dragon of order. So, most likely, Ascha granted them this ability. And besides, it was either Nival who came up with it, or Ubisoft gave the order. So, the questions should be directed to them.