For me it was Tanelorn by Blind Guardian. Hair metal in my head, all afternoon.
Sure Zoroastrianism had it's impact ('tho I'd argue that had bigger impact on Tolkein -- "keeper of the sacred flame" and all that) but I'd also throw out Chaos, the first god, as an influence:
https://en.wikipedia.org/wiki/Chaos_(cosmogony)
If you listen to any interviews with Moorcock he'll list influences all day -- his modesty is one of his better traits.
