Rhythm of war Easter egg in way of kings
I'm on my second listen through, and just noticed something fun,
When Shallan is researching soulcasting at the Palanaeum after she's stollen the soulcaster from jasnah she finds a book that says humming can make soulcasting more effective. That line feels like a little hint towards Navani's research of the pure tones of roshar in RoW. Like if someone using a soul caster hummed the stormlight pure tone it could help in channeling the stormlight more ettectively.
I love seeing just how thought out the magic system was even this early on and just picking up little Easter eggs like that.