Complex sentence: As part of a new marketing ploy, Fall Out Boy released several songs on iTunes before the release of "Folie à Deux", which, when purchased, would go towards purchasing the entire album as part of the "Complete My Album" feature.
Split into simpler sentences: As part of a new marketing ploy, Fall Out Boy released several songs on iTunes before the release of "Folie à Deux". When purchased, the songs would go towards purchasing the entire album as part of the "Complete My Album" feature.