Music Theory
For the magic system in my book, I spent several weeks pushing myself through a crash course in music theory, the result of which was an integration of it into the narrative.
My magic system is split into two main types of music: conjuring and manipulation.
For conjuring, I used the circle of fifths as a table for different types of conjured magic. Each key (and the relations between them) has ties to specific elements. This is the foundation of magic in my book. Music players are able to play in certain keys to conjuring specific elements and spells.
Manipulation takes this one step further. For context, everything and everyone in the world of my book has a song. Manipulation uses these preexisting songs, and alters them by using modes. For this type of magic, music players play whatever song they want to manipulate in 5 of the existing 7 modes (Ionian and Aeolian are for conjuring). Each of these remaining modes (Lydian, Mixolydian, Dorian, Phrygian, and Locrian) manipulate the song in a different way, and by extension, the object they belong to.