Depending on the overarching visual aesthetic you've had in mind for the band, you could always borrow album cover inspiration from the likes of groups such as Burzum, Mayhem and Dark Funeral with a drawing or artistic editing of a place or structure relevant to the ancient teachings such as the Pyramids of Giza, the Temple of Karnak, the Acropolis of Athens, the Temple of Apollo in Delphi, Wewelsburg Castle, etc.