My experience has been that a meta-pantheon emerges out of the accumulating results of magical practice, and that this pantheon is mixed in regard to its sources. A Deity, Guardian, Power, or figure from one source (historical culture, stream of occulture, line of magical teaching, revelation, etc.) stands alongside others from other sources.

My own meta-pantheon includes Deities like Freya, Odin, Kali, The Morrigan, Hi'iaka, Ganesa, Raven, and Coyote--as well as figures like Morgan Le Fay, The Green Knight, The Classical Muses, Devil Duck, Cthulhu, totemic Redwoods, Squat of Parking, and Wile E. Coyote.

I'd say that magical practice takes the practitioner into experiential polytheism. But I admit that, so far as I can recall, I was a polytheist before I started any practice.