Boots are used as a necessity for movement speed, but they lack heavy in the stat department. This build requires the use of boots up until the full build is complete, but allows for the user to gain some nasty stats that they wouldn't have been otherwise able to acquire with boots. With two phantom dancers still being a popular build by many people, I thought it would be awesome to work them in accordance with a zephyr allowing the ADC to go bootless late game (This due to the 5% movement speed on each phantom dancer, and the 10% movement bonus on the zephyr).