Keeper of the ancient art of Wuju, Master Yi is a mystical warrior from the isle of Ionia. He descended from one of the few tribes dedicated to the preservation of Wuju, a martial art founded with the principles of absolute spiritual awareness of one's self and one's enemy. When the armies of Noxus invaded Ionia, Master Yi joined in the Ionian defense to fight the craven enemy, bringing his village honor through his unparalleled mastery of the blade. The ensuing battles ravaged the land, but no conflict inflicted as much horror as the day the armies of Noxus closed in on Yi's village. Left undefended, the village became the unfortunate test subject of the latest invention by an up-and-coming chemist, now known as Singed. The remains of the village that Master Yi returned to were so horrific that it remains a festering scar on Ionian history. To this day, no Ionian will ever publicly speak of what occurred.

After the Noxian invasion was contained, Master Yi fell into a deep isolation. For years, he trained morning to night, speaking to no one and refusing offers of consolation by fellow Ionians. The only thing stopping him from madly charging into Noxus battle lines headfirst was his pledge to keep the Wuju style alive. Even though he seethed with impatience, his rage became a tool for sharpening his practice of Wuju, developing stronger and deadlier skills for his eventual vengeance. The only thing that roused him was news of the League's formation, and Noxus's subsequent enrollment in the League. Master Yi now brings his mastery of the blade to the League of Legends with unflinching purpose: to avenge his kinfolk and end the predations of the Noxus once and for all.

"The art of Wuju lives on in Master Yi, and is plunged through the hearts of his foes." -- Soraka, The Starchild.

The goggles Master Yi wears are a techmaturgical device that was gifted to the champion by Piltover's own Heimerdinger, the Revered Inventor. Master Yi first used these goggles when defending his homeland from Noxus invaders in the time after the League has just formed and before Ionia had affiliated itself with the League. The goggles are fitted specifically for Master Yi; while someone else may wear them, they won't receive anywhere near the same benefit as he does himself.

The one-of-a-kind goggles, known as the "Seven Lenses of Insight", allow Master Yi to see across a wider range of the spectrum than normal people see. They also give him abilities not dissimilar to that of real world binoculars and telescopes. The goggles are synced to Yi's own magical resonance, allowing him to adjust settings without the use of his hands. He simply thinks what he needs, and the goggles act accordingly.

If asked, Yi will tell you he was born from wisps of the cosmos, and that is why he moves like the wind. Those who have faced him in combat know the bite of the Wuju Bladesman- he strikes twice, without warning, and is gone. Often, the only clue that you are about to be struck by Master Yi is the hiss of his blade as it parts the air.
Keeper of the ancient art of Wuju, Master Yi is a mystical warrior from the isle of Ionia. His village was steeped in Wuju, and his kinfolk were some of the few to carry the tradition into the modern day. That is, until the armies of Noxus came to Ionia, ravaging the land. Master Yi went to fight the craven enemy, bringing his village honor through his unparalleled mastery of the blade. However, in his absence, the armies of Noxus closed in and tested the latest invention of the chemist now known as Singed. What was done to his village is something of which Master Yi will not speak. However, he has brought his mastery of the blade to the League of Legends in order to avenge his kinfolk and end the predations of the Noxus once and for all.

Master Yi brings the art of the Wuju style in a way that makes his enemies falter. He is capable of fighting with lightning speed, as well as finding purchase behind the defenses of an enemy's armor. He can call on his inner fortitude, regenerating at an accelerated rate. Calling upon ancient forces, Master Yi can fold space, appearing behind enemy after enemy. He is even able to reject magic, rendering it useless against him.
Master Yi himself has studied the arts of Wuju for more than a thousand years. He is the oldest known living human on Valoran, but to gaze upon him, you would guess him no more than thirty years old. The art of Wuju lives on in Master Yi, and is plunged through the hearts of his foes.

Upon selection
"My blade is yours."

Movement/attacking
"A wise decision."
"Certainly."
"Do not fear the unknown."
"Follow my lead."
"I will show you the path."
"My blade is yours."
"Wuju Style!"
"We strike now!"

Taunt
"Your skills are inferior!"

Joke
"Wuju pass me that potion?"

His quote "My blade is yours" is a direct reference to the Warcraft III hero Blademaster, who frequently uses it upon selection.

The Chosen skin is a direct reference to the Jedi Knights of the Star Wars franchise.
This skin's lightsaber changes colors based upon Wuju Style's current state: blue (normal), green (passive), red (active). This is similar to the Jedi Knight games which had blue, yellow, and red lightsaber stances; each altered the speed and power of attacks.

Master Yi's Ionia skin may be a reference to the "red period" from the movie Hero, as both the art in background as well as the color scheme match.

Master Yi's Samurai skin is a reference to the noble warriors of medieval Japan: the samurai, who were skilled swordsmen. His weapon, instead of having its original look, has the shape of a katana, the weapon of choice among the samurai.

Master Yi's goggles were given to him by Heimerdinger.
Master Yi's entire kinfolk were killed with chemical inventions created by Singed.
Master Yi has vowed to keep the blade style alive.
Master Yi seeks the end on Noxus' predations.
Master Yi has recently started tutoring Wukong in the art of Wuju.

"Wuju" is a reference to two of the developers at Riot Games. Namely, Andy Woo and Jeff Jew.

"Wuju", or "Wuji", is the grey field a taijitu (the yin-yang symbol) is traditionally shown on, symbolizing "nothingness".

It bears similarity to "Wushu", the collective name of Chinese martial arts, mostly known as Kung-fu in western countries.

Master Yi's Meditate ability highly resembles a similar ability used by Yoshimitsu from the Tekken & Soul Calibur series, using both a similar stance and a similar effect (healing).

Master Yi was one of the champions chosen for the Ionian pool available during the Ionia vs. Noxus match. However, he was not one of the selected champions.

Master Yi's Highlander ability is a reference to the Highlander movie series.
Master Yi shares similar abilities with the hero Yurnero from Dota.

Master Yi's Alpha Strike ability is similar to Yurnero's Omnislash.

The term "Alpha Strike" was first coined by the US Navy to describe a large air attack during the Vietnam War.

The goggles Master Yi wears (known as the Seven Lenses of Insight) seem to be an over-exaggeration of trifocal Night Vision goggles, and according to his background, provide a similar effect, allowing him to "see across a wider range of the spectrum". They were made by Heimerdinger.

Passive : Double Strike.

"(Innate): Master Yi strikes twice every 7th attack."

Alpha Strike.

"(Active): Master Yi leaps across the battlefield striking up to 4 enemies, dealing magic damage to each enemy with a chance to deal 400 bonus magic damage to minions.
Range to first target: 600."

"Cost: 80 / 90 / 100 / 110 / 120 mana
Cooldown: 18 / 16 / 14 / 12 / 10 seconds
Magic Damage: 100 / 150 / 200 / 250 / 300 (+1.0 per ability power)

Bonus Damage Chance: 20 / 30 / 40 / 50 / 60 %"

Meditate.

"(Active): Master Yi channels, restoring health over 5 seconds. While channeling, Master Yi gains armor and magic resistance.
Cooldown: 35 seconds"

"Cost: 70 / 85 / 100 / 115 / 130 mana
Heal Per Second: 28 / 56 / 84 / 112 / 140 (+0.33 per ability power)
Armor & Magic Resistance: 100 / 150 / 200 / 250 / 300"

Wuju Style.

"(Passive): Increases attack damage.
(Active): Master Yi can activate this ability to double its effectiveness for 10 seconds, but this removes the passive bonus until Wuju Style becomes available again.
Cost: 40 mana
Cooldown: 25 seconds"

"Bonus Attack Damage: 15 / 20 / 25 / 30 / 35"

Highlander.

"(Active): Increases Master Yi's movement speed by 40% and attack speed for a few seconds, as well as making him immune to any slow effects. Additionally, killing a champion during the duration will refresh all of Master Yi's ability cooldowns, while assists will refresh them by half.
Cost: 120 mana
Cooldown: 75 seconds"

"Attack Speed: 40 / 60 / 80 %
Duration: 6 / 9 / 12 seconds"

Master Yi can be hit with a spell that was already in travel before Alpha Strike is used.

Example: Sion casts his Cryptic Gaze before Master Yi uses Alpha Strike, Cryptic Gaze will land once Alpha Strike is finished.

When Highlander refreshes Wuju Style, its passive attack damage will stack with its active, thus giving 45 / 60 / 75 / 90 / 105 attack damage.

Activating Wuju Style a second time, after the cooldown has been refreshed by Highlander, actually results in a decrease in damage, as it eliminates the passive-active stack.

Attacking turrets will increase the counter for Double Strike and proc the double hit.

Master Yi's Double Strike is similar to Caitlyn's Headshot. It is very useful when farming enemy minions. Gathering stacks on it by attacking minions, then attacking the enemy once the double strike is available is an effective harrassment method.

Alpha Strike's AoE component has a deceptively long range. Target minions near an enemy champion to harass them.

Alpha Strike can also be used defensively. Since it includes a teleport function, you can dodge skillshots. Also, Master Yi is invincible during the teleport, so Alpha Strike can be used to dodge AoE nukes such as Nunu's Absolute Zero if timed perfectly.

If you're in a lane against ranged players, leveling up Meditate can allow you to stay in the lane longer and gain levels faster than they will.

Use Meditate, when in mid-clash and you are being focused upon. Enemies overly committed in killing you will find you surprisingly difficult to kill since Meditate grants 300 armor and magic resistance at max rank.

Meditate is especially useful when an opponent is trying to turret dive against Master Yi. He can stand next to the turret and use Meditate to hold off damage from the opponent while they are repeatedly being hit by the turret.

When you are being chased, hiding in a brush and channeling Meditate can give you the upper hand against the enemies. However, do not do this if they can still defeat you after the Meditate.

Be aware that Blinds can effectively cut almost all of Master Yi's damage if not playing Ability Power builds.

When playing Ability Power Master Yi, remember that Highlander refreshes all your cooldowns on a kill. Try to cast Alpha Strike so it will result in a kill. This may seem like kill stealing but it will greatly increase the damage the other team will take.

Highlander can be used as an effective escape tool, especially with Ghost used at the same time. it is also incredibly great at chasing enemies because you cannot be slowed and gain a speed boost.

Triggering Wuju Style and Highlander when combined with various melee increases makes Master Yi a high damage dealer, if for short periods. It's especially effective in destroying towers.
Wuju Style combined with Alpha Strike are very strong for last hitting minions.

Master Yi can jungle with Alpha Strike giving him a chance to hit extra damage to neutral creeps.

Master Yi is one of the best backdoorers, Activating Highlander and Wuju Style then attacking a turret can take it down very fast.

Since Master Yi is an effective DPS/Pusher, it is best to build him with damage and attack speed runes. Life Steal can also be useful with increased damage and attack speed but not necessary.

Consider that while his abilities are good, they work with relatively high cooldowns, meaning that Cooldown Reduction items are great to increase his overall use of abilities.

Master Yi is extremely vulnerable to Crowd Control abilities, especially Blind and Snare, so players are recommended Cleanse as a Summoner Spell to counteract these effects.

Quicksilver Sash can provide good results in surviving; the active "Cleanse" effect is very useful for countering CC, one of Yi's biggest weaknesses. The Magic Resistance also helps against return damage from Thornmail, a primary counter to Yi. Banshee's Veil can be used similarly.

Banshee's Veil is also useful for Yi because he is vulnerable to CC , Giving him the capability to block one spell.

Master Yi is a great pusher, especially when using Wuju Style and Youmuu's Ghostblade. However, Highlander shouldn't be used (if not necessary) since it enables him to escape ganks quickly.

Using Highlander and the active effect of Youmuu's Ghostblade at the same time is very effective in many situations since both of these have great attack speed and movement speed bonus.

Generally, items that provide bonuses on attacking or subsequent attacking are more useful on Master Yi than on other heroes due to his passive and high attack speed.

A hybrid Ability Power based Master Yi can yield good results, with items such as Lich Bane or Trinity Force, especially if your enemies are packed with armor.

A full Ability Power based Master Yi can pull off fairly good results. His Alpha Strike becomes a fairly strong AoE nuke, and is refreshed instantly if a kill is scored while Highlander is active. Your Meditate also heals and protects for a lot more than it did before.

Pairing Master Yi with items like Phantom Dancer, Berserker's Greaves or Sword of the Divine can greatly increase his dps.

Starting Youmuu's Ghostblade at level 1 by purchasing a Long Sword and choosing Wuju Style allows for a very effective last hitting and a high damage output. That gives you 15 bonus damage and when Wuju Style is active you will have 30 bonus damage.

Sword of the Occult works exceptionally well with Master Yi, as after level 6, and even before he is able to rip through most casters with ease, creating a powerful snowball effect.

Due to his high damage output, and 'Right-click-to-win' play style, along with being very easy to use and only 450 IP makes him great for low level games. However, against competent players, he is arguably the most difficult champion to use in the game, because of his extreme fragility and vulnerability to Crowd Control effects.

By buying a Spirit Visage, Master Yi can heal more effectively with his Meditate whether building DPS or AP.

Riot's Recommended Items.

Doran's Shield
Berserker's Greaves
Youmuu's Ghostblade
Last Whisper
Guardian Angel
Stark Fervor

MOBAFIRE's Recommended Items

Berserker's Greaves
Chalice of Harmony
Infinity Edge
Madred's Razors (Builds into Madred's Bloodrazor and Wriggle's Lantern)
Meki Pendant(Builds into Chalice of Harmony, Fiendish Codex and Tear of the Goddess)
Phantom Dancer

Meki Pendant -> Fiendish Codex -> Deathfire Grasp or Morello's Evil Tome or Nashor's Tooth.
Meki Pendant -> Tear of the Goddess -> Archangel's Staff or Manamune.