This is a fun made guide, I am not a pro or anything, just tested it out and it worked fine, with me killing 3 people without a scratch, well... it is not guaranteed that it will offer any wins.
So lets get started, i just noticed yi was too squishy and that he dealed a lot of damage so why not combine all of his kit in one build that would give him enought survability right?
Start of with dorans ring, get tear of the godess and vampiric scepter, get botrk and then the muramana, then buy frozen heart and wits end, later on get an hp item like rod of ages, it provodes a good amount of hp, mana and some ap that is used on his meditation.

One last thing, never die :P



Master Yi Build Average Stats:

Health 2592
Health Regen 18.45
Mana 2847
Mana Regen 21.6
Armor 95.59
Magic Resist 90
Dodge 0
Tenacity 0
Movement Speed 400
Gold Bonus 0
Attack Damage 206,62
Attack Speed 2.013
Crit Chance 0%S
Crit Damage 0%
Ability Power 80
Life Steal 19%
Spell Vamp 0
Armor Penetration 0
Magic Penetration 0
Cooldown Reduction 25%