This Vintage-legal loop hinges on Elsha of the Infinite letting you cast noncreature spells right off the top of your library. By utilizing the colorless mana from Mana Crypt alongside the blue mana generated by Mystic Sanctuary, you have just enough juice to cast Ghostly Flicker. When Ghostly Flicker resolves, it blinks both Mana Crypt and Mystic Sanctuary back onto the battlefield. Because Mystic Sanctuary enters untapped, its triggered ability lets you place Ghostly Flicker right back on top of your library to repeat the cycle infinitely.