User blog comment:Kharjou/ADC tips chosing first big item/@comment-4743916-20130409013002

The fact that you are focusing so heavy on the numbers rather than just playing the game and feeling out what would be appropriate for the situation means that you're probably not going to get the answer you're looking for from us. Everyone has their unique reasonings for building whatever items they go and their experience from messing up reinforces these choices. I'd suggest you just play the role enough that you become familiar with what works for you and what you find is most appropriate. Honestly, most pro players don't even mathcraft as hard as you just did besides generally knowing tidbits like MF having high base HP and such so if they can win without that kind of math, you probably can too.