Here is another idea I have been kicking around. I don't know if I'll finish it, and if other people like it and want to run with it, feel free. Anyway. In the same vein as others already, I thought I'd do my own "hidden world guide" to New York City. So, I hereby present the opening draft of the Modern Arcanists Guide to New York City. One of the conceptual differences is that "ley lines" are byproducts of the interference between Energy Focuses; if they interact well you would get a ley line and if they don't they'd make null-spaces.
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