User blog comment:Centuriarch/Different ADC build./@comment-4022742-20140313130253

Generally speaking you have a pre-set slot distribution as a marksmen, usually following this setting: Some people opt to omit the defense part to get more utility or damage, all in order to have a leg up on the oponent, which is fine as long as you play something slippery or long range like vayne, ez, or tristana.
 * Movementspeed (Boots, Zephyr)
 * Sustain
 * Main Damage
 * Utility
 * Penetration
 * Defense (,

However in most cases this recipe works out to be the most optimal way of playing a marksmen. You can swap out any of the items in a category, but only if you get something of equal value in return. would take up the spot of Utility, which looses you mobility, crits and other benificial stats. For it to work you need to make up for it in the Defense department, taking something like Zephyr instead seems to be a fine play.

Sticking with the standard is better for serious games. If you're here to have fun though, go for it!