is the champ with the biggest damage in lol.He is a high-risk high-reward one but if you master him you can make miracles.He needs lots of experience to be played effectively in higher rankings and skills too.He is not just right click like most people say >.<.
I made it till Diamond because of him and i am here to introduce the way i played him to reach that level.
I am just 15 years old now and my english might not be that good but Bear with it xD.

You just have to focus on taking Attack Speed runes to release the biggest potential of

Just maximize the OFFENSE attributes since it's yi we are talking about ^^

I try maximizing 's Damage and after a lot of research i Made the current build you see.
varies from his Damage,Critical and Attack speed i dont take lifesteal since i clear my opponents fast enough and they dont have enough time to cast speels on me or do me damage.
The core items are Infinity Edge and Phantom Dancer
This item build made me to go where i am now..

Maxing Alpha Strike then Wuju Style and then Meditate is the right skill order by my experience
We ussually max Alpha Strike then Meditate and then Wuju Style when we have a long-ranged enemy like

Flash is the most effective spell on yi since with this you can assasinate your opponents or suprise them
I prefer Barrier/heal rather than ignite since my build doesnt have lifesteal in it
Ignite still is a viable option if you have opponents with high lifesteal skills or lifesteal reliant for example with enemies like or

In early game you have to focus on FARMING(MOST IMPORTANT) and killing your enemy as fast as possible.Try if getting LEVEL 2 first to kill him before he hits 2 too.Always have in mind your opponents cc abilities and when he has flash or not.At level 2 you can beat all enemies except irelia size 50,jax size 50 and renekton size 50
In mid game if you have not snowballed and you just have to farm until you get Your core items which are Infinity Edge& Phantom Dancer.
In late game you can easily beat your opponents with my build your opponents will die in a matter of seconds but you must not go in the front line like an idiot or go in first,I ussually get behind my enemies and focus ADC>APC>SUPPORT>TOP OR JUNGLER>TOP OR JUNGLER

Pros
BIGGEST DAMAGE IN-GAME
SLOWS ARE NOT EFFECTIVE
TONS OF TRUE DAMAGE
HIGHEST SPEED IN GAME WITH HIS ULT ON
AMAZING YOUR TEAMATES AND OPPONENTS ;D
Having tons of fun

Cons

Very squishy
Mostly focused target
You have to be very aware of your position
If you fail early you failed probably the whole game
if you fail early you are probably useless late ;p

In teamfights you have to wait until one of your teamates gets in first.
1ST YOU HAVE TO HIDE IN BUSH AND WAIT TO STRIKE FROM BEHIND
2ND FROM BEHIND THERE IS PROBABLY THE ADC AND APC FORCUS THEM
3RD PENTAKILL!!

Try dodging the enemies skills with your Alpha Strike it will need a lot of work and experience to do that+ a good pc without lags ofc
Wuju Style can penetrate your enemies tanks ;DD I SO LOVE IT
Meditate conpensates the lifesteal i dont buy + it gives bonus durability stats while you are at it in case you are 1v1 with an enemy and you are waiting your spells to pop again or cases you just need ARMOR AND HEAL TO ESCAPE DEATHS ...

Farming?i dont think you will have a problem with yi and newbies can easily farm with Alpha Strike if you cant last hit

Always remember in queue if you are first pick you have to ban and
Your teamates may start flaming you during queue because they believe
is a low pick.
Mastering the master is a hard job and you have to be 100%FULLY Dedicated

:He is a Medium level opponentif you want to beat aatrox you have to beat him either on lvl 2 or at lvl 6I suggest you to pick Flash and Exhaustagainst him.
Note:if he beats you early i suggest you to request your Jungler's help in order to beat him

:She is an easy opponent just buy oracle's ward which costs 100g or Oracle's Lensjust her early spam is annoying but bear wit hit ;p

:He is a medium opponent it all depends on how you do before level 6!!I suggest you put Flash and Barrier or Heal since you can reduce Ulti.

:He is an easy opponent with the burst you have and with the correct spells which are Flash and Ignite you won't have a problem.

:She is a difficult opponent.Her early burst and long range spam is REALLY annoying as a tip for here you just have to max your Meditate and request your jungler's help.

:She is an easy opponent.You just have to pick Flash and Exhaust against her.When she ulties you just have to Meditate or completely making her ulty useless by Alpha Strikeing a minion.

:He is an easy opponent.His silence is useless against yi since he is basically an aa champion.Just keep in mind he has ulty in level 6.As spells against him pick Flash and Heal.

:She is the MOST DIFFICULT MATCH UP.You just cannot beat her 1v1 try farming as much as you can and max your Meditate.As spells against her pick Flash and Ignite.

:He is of course a hard match up for yi.Just by having his Counter Strike which dodges your basic attacks will make it hard for you.Experience players like me can dodge his Counter Strikethough that means with practice you can do it too guys.As spells pick Flash and Exhaustif you are inexperienced but i ussually pick Flash and Barrier

:She is a medium oppoent if you know how to counter properly.In laning phase maximize your Alpha Strike and Meditate because her spam is annoying..She is one of the real troubles though at lategame so tell your teamates to cc her in order for her to not use her Interventionand dont focus the targets with Interventionmy build is not tanky enough for you to hit nothing for 2 secs at the middle of the battlefield.

:he is an medium opponent at the laning phase.Max your Alpha Strike and dodge his Shock Blast.If enemy picks jayce it actually favors you because they probably won't have a good tank and you can kill them in a matter of secs..

:He is an easy opponent.Squishy and 1v1 reliant he is you can beat him just dont fight without creeps aroundyou.Just dont screw up with him at early levels and you should be fine.At level 6 i suggest you to buy oracle ward since his ult is annoying.

:He is an easy opponent.your burst is bigger than him try dodging his q being between creeps and you are fine.His ult is the most annoying though since it you are vulnerable with the knockback.

:He is an easy opponent.At level 6 with your Highlander and by having Barrier as one of your skills he won't be a problem.Just dont get killed a lot early because he can easily tank you though.

:he is an easy opponent but beware of his lategame.Pick Ignite as one of your spells and you won't have a problem.Try pwning him at early and mostly when you have Highlander ;DD

:He is a medium opponent.His true damage is the real deal.With this match up only the most skilled one will be victorious.I still havent figure which spells are most effective against him.With a cc jungler though you can kill him easily.

: He is a difficult opponent.Since he is effective only at laning phase just purchase Cloth Armor and 5 potions.

renekton size 100:The most picked top laner right now and he is an difficult opponent.I suggest you to purchase Cloth Armor and 5 potions +never fight him at the laning phase ALONE

:She is an easy opponent.Hold your Alpha Strike to doge(i am a fan of him)her 3rd Broken Wingssince she is a squishy opponent pwn her early and you will not have anyyy problems.

:She is an medium opponent.She is 80%ap and tanky too it all depends on how you do early.

:He is an medium opponent.It all depends on the most skilled one here.For help i suggest you pick Flash and Barrier.