Thanks for the question, Kirowan.
Spectrum mechanics are an addon that expands on the standard magic system. An area might be aligned with a certain type of magic, say 'Profane', while edging out other magics, such as 'Benevolent' energies. Spells and magics that fall under the heading of 'signature magiccs' are enhanced, while 'countersignature magics' are hindered. By combining these descriptors in unusual ways, you can recreate a wide range of fantasy and mythological locales. You can recreate any type of place of power you can imagine with spectrum mechanics. These are scalable, as well, from weakly aligned areas that show their influences in subtle ways, to areas suffused with more power than the planes.
I think there should be enough information in this section of the book to use any magic system you want (Such as Elements of Magic), though the the system was designed with PHB magic in mind. I kept it open ended, since I've been thinking of developing an alternate magic system for a while.