The function of Apollo as a "healer" is connected with Paean (Παιών-Παιήων), the physician of the Gods in the Iliad, who seems to come from a more primitive religion. Paeοn is probably connected with the Mycenean pa-ja-wo-ne (Linear B: 𐀞𐀊𐀍𐀚), but this is not certain. He did not have a separate cult, but he was the personification of the holy magic-song sung by the magicians that was supposed to cure disease. Later the Greeks knew the original meaning of the relevant song "paean" (παιάν). The magicians were also called "seer-doctors" (ἰατρομάντεις), and they used an ecstatic prophetic art which was used exactly by the god Apollo at the oracles.
What were magicians also called?
seer-doctors