Master Yi Can be very dangerous after you complete your build

You can Also add Mana Regeneration Runes if you use Cooldown Reduction Per Level Runes.
That helps you save mana and activate alpha strike many times...so you can easily farm and getting kills

For Masteries i choose Armor Penetration
Attack Damage, Critical Strike, Lifesteal Attack Damage

With these items you can cause a lot of damage to your opponent
Frozen Mallet Helps you to slow your TARGET you also have high Heatlh points and attack damage
so your Exhaust will be uselles but you can add Ignite.It will help you to your early game :D
Berseker's Greaves gives you Attack and Movement speed it's a good choice to because in early game Master Yi needs
Bloodthirster It's a awesome item Damage + Lifesteal and a great passive (so that's why you dont get Meditate too early because of lifesteal :D ) And you can recover all your health again
from battles so you gonna be ready for the next ones :)
Phantom Dancer 3 on 1 it suits very much on Master Yi you can use another one if you want. You can have a great combo by having this item with Bloodthirster and Infinity Edge
Infinity Edge So with this you will have great damage and critical strike (99% if you have two Phantom Dancer )

Black Cleaver I suggest you to buy this when there are too much tanks in your opponent's team because it causes pierce damage...Build it instead of a second Phantom Dancer

Yoummu's GhostbladeYeahhh!! Critical Chance + Damage and Cooldown Reduction...Pretty Cool...If you like it build Master Yi with this way

So in the end Master Yi will have 1.5 attack speed 200-300 atack damage 81% - 99% critical strike and lifesteal ;)

You should finish this first as soon as possible it good for farming and chasing your opponent
As you have life steal i suggest you to dont use it and max it last

Amazing Skill to kill your opponents easily...just dont waste it i usually use it in pvp battles and of course to destroy turrets when im in hurry
This is the Ultimate skill of Master Yi use it only on battles not on minions...so if you are in a difficult situation you can use it to have much attack speed + Bloodthirster + Infinity Edge = Great Damage.You can also use it to get many kills and then you will recover your Cooldowns

You can also use this spell to use this as a finisher when your opponent.Also its good to get kills during early game

It's Incredible to use it by passing through the walls you can escape with this or to reach your opponent when he's escaping with too

Well if you have as an oppontent a or a or different champions as opponent, this spell will be your friend :D you remove stuns slows silences blinds buffs and de-buffs.Lol good also to counter against Exhaust and Ignite

If you dont like using Phage - Frozen Mallet try using this instead of Ignite

Why Not?

If you are so PRO and you easy-killer try this you can save your turrets and catch your opponents in a difficult situation- Low Health points - not purchased items and near turret :)

Usefull to combine this with Highlander

Nooooooooooooooo Man!!!!

Just dont do it because you have your ultimate Highlander

PROS

+Great Farmer
+Easy Player
+Amazing Chaser
+Very Good Jungling Speed

Cons

-Squisy
-Saved only from turret and Meditate but with meditate in early game is difficult for kills
-Not CC(except if you play AP)
-Waster Of Mana Points
-Pro Killer only with completed Build
-Long-Time Cooldowns

Early Game 1-6 lvl

Alpha Strike
While you Have Phage and Zeal it's easy to get kills/***iss and farm
try to kill minions with [[alpha strike if you arent going well in this game and if you haven't got these items I have mentioned above

Mid Game 7-12

Try the same as above ( etc. )
You have enough gold now buy The Bloodthrister and Phantom Dancer
try hitting minions with basic attacks if this isn't enough just use also

Mid Late Game 13-18

Now by having Bloodthirster, Phantom Dancer and Infinity Edge it's easy to farm...farm to recover your life with lifesteal and to earn gold to complete your build ( Frozen Mallet Black Cleaver or a second Phantom Dancer