Maga
Looks like the Maga term we use originally came out of Zoroastrian religion, and was used as one of the oldest terms term for a fellowship of Magus (The ‘Magus’, then, would be the man possessed of Maga ), Magi. Also that it’s adherents worshipped Indra the God of The Storm
Maga has been mentioned six times in the Gathas Although interpretations differ as to whether it means a " difficult task, enterprise" (Kanga & Insler), or "gift and reward," I, following Bartholomae and Taraporewala, derive it from maz/mah to mean "magnanimity," the name Zarathushtra gave to his universal Fellowship. It is twice called maz maga, "Great Fellowship" in the Gathas with a view to emphasizing the importance of the movement started by Zarathushtra. Magavan means "belonging to Maga" and therefore a "companion of Zarathushtra, Zarathushtrian."In the Gathas, it does not give the meaning of a religious leader but a person belonging to the Great Fellowship.
Although the Gathic magavan, member of the Zarathushtrian fellowship Maga, has never been used in the Later Avesta, Old Persian magu (Greek magoi, English magus, plural magi) and the subsequent Pahlavi magopat, mowbad; Persian mobad, mobed) mean a member of the priestly class. There are eight functional terms: zoatar, hâvanân, âtrevakhsh, frâberetar, âberet, âsnâtar, raethwishkara, and sraoshâvareza.
They were also known as Magavans, belonging to Maza Maga, the Great Magnonimity, the Great World Fellowship founded by Zarathushtra. This term gave rise to Magu priests of a Median tribe.
Magu in Old Persian, and its subsequent terms of magus (plural magi), magian, for members of the priestly tribe of Medes during Median and Achaemenian periods in Ancient Iran indicate that in later times, the word became related to a priest and the priestly class. Nonetheless, the Pahlavi magog, Persian mogh, Arabic majûs meaning "Zarathushtrian" and magopat, "head of mago(g)" and therefore a priest show that it continued to be applied to a member of the Zarathushtrian fellowship and not necessarily to "priest." Furthermore, maga is rendered magîh, magianship with a gloss "pure goodness." It is a generic term.