Ahura Mazda, the Iranian sky god, the Wise Lord or Lord Wisdom was the god of the ancient Zoroastrians.
The scriptures of Zoroastrianism, the religion developed by the prophet and savior Zoroaster.
A basic summary of what the ancient Zoroastrian religion is about.
What Are the Attributes of the Zoroastrian Amesha Spentas?
The helpers on the side of order, truth, and the good --- that is, on Spenta Mainyu's side --- are sets of pairs active on the personal level for humans and for the good of social units, like nations, as well as on behalf of the non-human elements in the world.
Yazata is a term for a type of ancient Iranian 'god', using the word very loosely, since they generally were not what we would recognize as the humanoid gods of the Greek and Roman pantheons or the paternal figure of the Judaeo-Christian tradition.