In a nutshell, it's a concept I took from Swords Without Master. The Tone is a word that will shape the fiction, the universe. When it's triggered, the Tone is applied to the whole scene : with the Cold Tone, ice could form where there is water, the weather would change, chill with go through spines...
It's a narrative tool, to show how the powers of the RadX are overwhelming the characters. It's kinda like when, in a comic book, a mutant (like Phoenix ?) has too much power and can't control it.