If you're just trying to beat a song, then glass is pretty bad. I'd use sap or perception instead (assuming you're not hitting enough perfects for needle to be worth it). It's really only when going for SS coins that glass starts really helping.
The most chaos I had was when I got yin yang and rolled ritual with it during a boss fight. Somehow they kept looping, with the rituals rolling a bunch yin yang and the yin yang rolling rituals, which meant that by the end I had a million modifiers. Good times. Game is good.