Hello, this is my first guide on my favorite toon Master Yi.
BASICALLY THIS GUIDE WILL CONSIST OF HOW TO ABSOLUTELY PWN WITH YI:
Hope you enjoy reading and learning from this guide as as much fun as i had playing and experimenting. THX! :)
-Shab
P.S Please vote and comment, i want TONS of feedback on how this works for you, give me your story!!
This guide is a laning guide, not a jungling guide. Do not play this guide to drag people into the forest to paint the forest, paint the road! ALSO- This guide is not a Push Button 1, right click win. It requires you to impliment skill and devotion. As with any toon, this guide just makes it easier to PWN :)

Pros(The preferred):
~Yi is powerful throughout the game
~Ultimate that refreshes on a kill(hell yeah)
~Good pusher/ harassing the enemy team (Alpha Strike's mass hits, far reach, and position reset)
~Highlander's ability to allow Yi to backdoor
~Can make or break a team
~Great passive
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Cons(The Unloved)
~OP Passive
~Mana pool is a joke
~**** for survivability
~ITEM DEPENDENT
~Expensive item investment

Greater Mark of Alacrity- Self explanatory. For this build, Yi requires Attack Speed.

Greater Mark of Desolation- Most teams on sight of a Yi will immediatly begin to apply Armor to their build, which unless you have SOME armor pen, migitates your damage delt, altering the life steal you receive from crits and regular damage. <-- VERY BAD!

Greater Mark of Malice- Critical Damage is good to add life-steal.

Greater Seal of Alacrity- (See Greater Mark of Alacrity for explanation on this Seal)

Greater Seal of Furor- Here's where people see the uselessness in this seal, your crit is a big part of your life-steal gain, crit harder, more life stolen.

Greater Mark of Malice and Furor- Already explained :)

For Yi, if your not Level 30, prioritize the Offense tree. Use your knowledge already on why i chose these Masteries, their mostly an obvious pick as to why these are good.
Especially Cripple(offensive tree) and Haste(Utility tree) if you let your enemy get away... your not a very good Yi, are you?
Also in the offensive tree, you want to hit harder, and into the Utility tree, you want to last longer don't you? Of Corse!!!

Berserker Boots- Attack Speed, run speed. Pure beauty. 1st item. PERIOD.

Phantom Dancer- Well look here. Attack Speed, Crit, and- what? RUN SPEED? Yup! This, even though dosnt act much on run speed, helps increase life stolen with its crit rating, and the run speed, like stated, if you let your opponent get away, your not a very good Yi are you?

Infinity Edge- Absolutely huge for Yi. Massive Attack Damage, and crit. All good for the ol' life-steal pal. BUT, its passive is breathtaking. Instead of a 200% crit damage( flat basic) your crits now do 250%!! *gasp* So imagine you crit Annie for 500, no Infinity Edge... NOW, you crit Annie with an Infinity Edge, chalk up another 83 damage So roughly 600+ DMG. Which would give you 30 life back on your life-steal. (Rounded estimations- accurate) <-- Done this before

Stark's Fervor- This baby has everything you need. Hold up, look at the passive! An AURA that gives your allies a 20% life-steal and attack speed! (It affects you too!!!) This is a very powerful tool for laning with another partner.

Black Cleaver- It not only gives you Attack Damage and Attack Speed, but its passive also acts as armor penetration( reduces enemy armor by 15/30/45- stacks 3 times)

The Bloodthirster- Again, gives Attack Damage desperatly needed, and life-steal. Its unique passive( does not stack) Per enemy kill, gives an attack damage and 1/4 of a life-steal, never mind the puny numbers, look at its full benefit- stacks 40 times. SO tha'ts a 40+ Damage and 10% Life-steal increase, a huge passive. By the time you get this, you should absolutely be pwning everybody.

Exhaust- Great for catching up to fleeing enemies. This and Alpha Strike are great buddies.

Ghost- Great for fleeing (not much for this later in game) and catching up to enemies if your Highlander is on CD or no mana to use Highlander

ALTERNATIVE SUMMONER SPELLS(Not recommended)
Using a Different spell then specified above will result in a absence of skill and goes out of conduct of the Masteries set above. (HASTE+CRIPPLE)

Flash- Teleport to or Away from enemies

Cleanse- GREAT for getting out of sticky situations for beginning levels, but with your life-steal and crit, you'l rip through people and still have alot of life left over for victim #2 AND 3.

Any other spell is worthless to this build.

Heal- Life-steal is your main concern, this is useless with life-steal.

Ignite- CAN be a good finisher. But goes out of conduct of your Masteries.

This guide shows the importance of stacking:
-Life-steal
-Attack Speed
-Critical Strike Chance/Critical Damage
Life-steal and Attack Speed are the main part of Yi. The quicker you attack, the more life you return to yourself (judging on the life-steal you have), as critical strike and increasing Critical Damage increases life-steal. Ultimatly this guide teaches you how to survive with Yi with life-steal, and wrecking enemies in its path. The different Runes/Marks/Quintessences/ and Seals i use all go with the three main parts of Master Yi.

NOT A JUNGLING BUILD, THIS GUIDE IS MENT TO BE A LANING GUIDE. SURVIVABILITY AND PUSHING TO THE MAXIMUM POTENTIAL. This guide eliminates foes in the open, not in the bushes. Dont drag them away to pain the forest, paint the road!

Great team ethical build. Laning support, and Stark's Fervor provide benefits. You can definatly save somebody's but with the speed of Master Yi. (Highlander, Ghost, etc;)

This build simple, and devastating. Binds Life-steal, Attack Speed, and Crit/Crit Damage together. Definatly unique not many Yi's will do this. Its potentially devastating if played correctly.