Master Yi Build
Not Updated For Current Season
First off, I would just like to say that the core of this build (90% of this build, moreso) is not mine. Credit for it goes to DEWO. His Yi build is outstanding, and I have had much success with it. However, when I play Yi, I prefer a bit more staying power. Having said that, I have only made a couple of changes. His fantastic build can be found here:
Master Yi, Cutting with Wuju Style. __(NOT A SPAM BUILD)__
Now, since you can read up on his playing style on the link above, I will not go into much detail. I will only list my playing style changes.
My substitution of Teleport for Flash is to make sure that when you need to recall for health, mana, or items, or if you die, you can quickly get back in your lane and continue racking up gold because this build is very costly, and if you can't keep farming consistently, you WILL NOT succeed. The way I play Yi, I only have two uses for Flash. Either I use it to chase an enemy down when Highlander is on CD, or I use it as an escape mechanism. That being said, the best way to stay alive is to avoid getting into situations in which the scales are not tipped in your favor. Even without Flash, you can still escape fairly easily because 1: Zerker Greaves + P. Dancer = Unparalleled speed, and 2: if it is an iffy situation, then wait to pop highlander because later in the fight, highlander will let you chase them down when they run or it will help you escape when things aren't going your way. The Teleport for Flash substitution is not necessary for this build, but I will usually take it over Flash for staying power.
Also, I made some changes to the item build. I start off with a Meki Pendant and two health pots. So right at the start, you are already balanced. You have mana regen. You have health pots so you won't have to recall as soon. And you have the Wuju Style passive, increasing melee damage. This is a good setup for staying power. Next you want to make sure you get your Boots of Speed so that you can keep up ok. Then build you Meki Pendant into a Philosopher's Stone. Not only do you have health and mana regen now, but you also have increased gold income, ultimately speeding up your late game, when you REALLY start to shine and make the enemies rage quit and throw their monitors out the window.
Now you get your Berserker's Greaves. At this point, you should be following DEWO's guide closely. I usually prefer to get my Infinity Edge before my Bloodthirster, but if you are still having trouble keeping your health up in your lane, getting The Bloodthirster first may not be a bad idea.
Once your build is full, there are a couple items you can swap out if you want. I usually switch my Berserker's Greaves for a Madred's Bloodrazor in the very late game. Also, if the game lasts THIS long (which it shouldn't, since you ARE Master Yi, and you can pretty much just right-click to win the game), then swap your Philosopher's Stone for the Tiamat.
At this point, you actually have the same build as DEWO's guide. It just has slightly reduced damage but higher staying power.
I hope this guide helps! If you feel a change should be made, then PLEASE comment below first before giving this a -1 and I will test it and make changes as necessary.
DEWO - for his comprehensive Yi guide