Hi guys this is my first build so please I'd like constuctive critism about it and I don't mind if you hate it. Anyway, Master Yi is a fun champion to play with, especialy with this build, if you get kills then it will surely be a win with this one :D

So lets be clear, Yi isn't great as an overall champion, i have tried AP builds and they don't really deliver in-game since Yi relies too much on his regular attack so:

Pros

- Fast attack and movement speed champ
- Obvious ganker
- Ulti makes for ideal chaser
- Meditate can help in lane (I don't use it much considering this isn't an AP build)
- Alpha strike = easy minion kills

Cons

- Squisher than a sponge, I won't dare a team fight unless I know I'm gonna get a kill
- His ulti doesn't protect him from stuns that means a well timed stun means a dead yi
- Thornmail is Yi worst enemy an opponent with that is a no go, unless there low on health etc
- Generally any high armor champion will be an annoyance to Yi but if your build is near complete there is nothing to worry about

So now I'm just gonna go though the items and justify why I get them:
Boots of Swiftness
These are not always an ideal choice but they certain are early game chasing champions, even more so with Highlander.
Phantom Dancer
This item is very crucial to Yi's build and has excelent synergy with Infinity Edge, providing everything Yi needs. get two of these until your build is complete so that if your feeling lucky you can sell your boots and buy another, gotta love 100% crit chance :3
Sword of the Occult
of corse this is providing kills are a thing that occur often, but with 20 stack Yi is gonna love that bonus movement speed and the damage bonus is devestating. If stacking items are not your thing, get another Bloodthirster and you should still be good on damage output.
Infinity Edge
This item is awesome combined with Phantom dancer with this build you will crit 80% of the time and 50% harder with the passive (plus another 10% with mastery), that makes this item a no brainer
The Bloodthirster
I love this item, but only get it late game, (or after you get 2 Zeals, it you don't want Occult). it should be your last or second to last item - I'll talk about item setup next.

I'm goind to be brief on how to play Yi, its relatively straight forward, just be careful and aware and you should be fine.

Early Game
Get boots and 3 potions, honestly I start most champions with this, its real easy as its a good opener for any champ.
When getting items I would get boots if I don't have enough gold for Zeal, but if I do the girst time i get back I would buy one then get boots, just decide for youself.
If your getting kills then get an Occult as soon as you can afford it.

Mid Game
This begins with this guild when you have boots and 2 Zeals and Occult, hope you stock up on potions up to level ten there still handy until that level. Here your gonna have to stop roaming the map ganking anything you can, make sure there on there own and initiate first. Build up those stacks since thats what your relying on in terms of damage contine to save up for either a Bloodthirster of Infinity Edge, again you choice on what comes first, personally I would get a Bloodthirster first for epic life steal (if your on 20 stacks then just a one Bloodthirster will give you enough lifesteal fully charged). On the other hand if you didn't get an Occult then two Bloodthirsters will be real nice.

End Game
By this time Yi gets hard to play. Team fights will occur often with no one going solo. But you will have really powerful DPS with all that attack speed, attack damage and lifesteal. you will unfortunately be super easy to gank. Stick to a tank or other tough Champion that the other team will hopefully target. anything apart from a tank will be easy to decimate with Highlander on, just be weary of any champion that can obliterate you, any high output champ can just don't rely on you lifesteal since even with your epic DPS you can't and won't get enough off a whole team especially with a snare or stun on you. Any decent player won't be a fool, so try not to lose stacks if you have them.

Thats its for the guide, hope you find it helpful, remember not to specifically follow the build, you could get sword of the occult before anything if your racking up kills early on, or get Infinity Edge before upgrading your Zeals, mix and match for different mid game results :D
Please do give some decent comments on what you think they will be much apreciated.

i will say that I would expand further but if you know LoL you'll instant think to yourself in a game,"Oh thats Sion he has a stun better be careful of him" or,"Hey theres an enemy Morgana she has a snare better be carefule of her". Thinking is not hard guys use your noggin and you will be fine.