I'm back.

First of all, I'm open to all comments in order to improve the guide. I will be glad if you share your opinions from the comments section. Thanks from now!
I'm just an armless and skilless League of Legends player. I was playing the game so frequently but after season 7 I started to play less. I don't usually play ranked. I have so many accounts and I can't calculate how many mastery points in total I have, but I play Master Yi very frequently. Sorry for my bad English.
Work in progress, btw. Sorry for slow updates, it's a little hard to make all the work from phone.

Master Yi is a champion who can deal unmatched and continuous damage in a long time. If enemy doesn't have hard CC, you will be unstoppable.

+ Unmatched damage in late game
+ Good against skillshot based champions thanks to his high MS and Q.
+ One of the two champs who start with the maximum MS (355). Other champ is Pantheon.
+ Has a gap closer (Q).
+ Ult for both engaging and escaping
+ High outplay potential
+ Easy to master
+ Can 1v9

- Vulnerable against hard CC
- Gets poked easily and can't answer it.
- Relatively weaker early game.
- Relatively squishy.

Passive: Double Strike After your third AA, you will strike twice. The second strike deals half damage. That's all. You deal more damage and your Q resets faster. If you have Guinsoo's Rageblade with 6 stacks, your passive will trigger frequently.

Q: Alpha Strike Cost: 50/55/60/65/70 Mana Damage: 25/60/95/130/165 (+100% AD) Physical Damage Range: 600 Master Yi teleports to the target, hits to his target and maximum of 3 more random targets around his target (Other 3 hits do %15 damage.) . Every AA will reduce this skill's cooldown for 1 second. This skill is your gap closer and it will be best to use it for dodging at least 1 skill. If you have Guinsoo's Rageblade, you will have frequwnt Qs. It can deal critical damage. Also it deals bonus damage to monsters so jungling will be easier.

W: Meditate Cost: 50 Mana Heals: 120/200/280/360/440 (+100% AP) HP over 4 seconds. Damage Reduction: 60/62.5/65/67.5/70% damage reduction for 4 seconds. Master Yi channels for 4 seconds. Gains damage reduction and heals himself while channeling. It will heal more when your HP is low. In my opinion, damage reduction is more precious than healing so you can ue this skill while fighting to reduce the damage. Also keep in mind that while channeling, your passive will be stacked over time and pause your ults duration.

E: Wuju Style Cost: 0 Your basic attacks deal 18 / 26 / 34 / 42 / 50 (+35% bonus AD) True Damage for 5 seconds. This skill is for dealing true damage and it is extremely useful for melting tanks. Nothing more. But it's so effective.

R: Highlander Cost: 100 Mana Passive: Kills and assists reduce your basic attacks' current cooldown by %70. Active: Grants 25 / 45 / 65% attack speed and 25 / 35 / 45% MS for 7 seconds. Kills and assists increase Highlander's duration by 7 seconds. Your engaging and escaping skill. Very powerful for fighting as it gives huge amount of attack speed. More AAs mean more Qs, so you can dodge more skills.

Precision runes are the best for Master Yi.

Except Fleet Footwork, the 3 other runes works well with Master Yi. Press the Attack gives bonus damage, Lethal Tempo gives bonus attack speed and lets you have higher attack speed than 2.50 limit and Conqueror rune goes very well with Master Yi. In my opinion, take Conqueror %90 of the time.

Triumph is the best in its line. It increases your outplay chance and synergizes with your ult.

I personally prefer Legend: Bloodline. You can optionally take Legend: Tenacity. Extra attack speed might be a good choice because it boosts your early more than others but it won't be effective as the others.

Last Stand for dealing more damage when you are about to lose the trade and want to turn the tables. Coup de Grace will be the best if you will focus on assassinating enemy carries and it will be useful for jungling. Cut Down can be a good choice in the laning phase against tanky champions.

Domination for second runes.

For more sustain especially in the laning phase. Can be replaced with Sudden Impact especially when you are the jungler.

For more sustain. Relentless Hunter can be a good choice too especially if you are a jungler. But if I were to choose one, I would pick Ravenous Hunter.

No need to explain; it is useful for chasing, escaping, engaging... DON'T CHANGE THIS Spell. (But you can take Ghost and Ignite vs. Singed actually.)

Good against champs with good sustain and tanks like Dr. Mundo who has huge health regeneration. Also it can secure kills and helps you to get early kills.

For chasing or escaping from champs like Singed or Udyr who are as mobile as you are.

For split pushing, map pressure and minimizing minion loss. Can be useful but in my opinion Ignite or Ghost are more useful.

Removes CC and can be very useful when you are behind. Useful against champs like Morgana as they can stop you in teamfights. But you can take Ignite and Quicksilver Sash, so you will have like 3 spells.

Classical AA item. Has a cool passive and active. It gives you good stats.

The boots you will be buying %90 of the time. Can be replaced with Mercury's Treads when against hard CC or heavy AP, or with Ninja Tabi against heavy AD.

Another cool AA item. Passive and stats, all good except AP. Your passive will be triggered frequently and your Q's cooldown will be reduced significantly. You will have frequent Q's and you can easily switch your target. For example, if you start stacking Guinsoo's on a tank and when a squishy target appears, you can easily change the target as your Q will almost always be ready.

Against burst damage and it has nice amount of AD and HP. Good against your major threats or champs whose 1v1 is strong.

Good slow and HP. Combined with Sterak's Gage, you will have a huge shield as Sterak's gain its shield from extra HP.

Effective against tanks. Gives movement speed which increases your sticking power. Also gives cool base stats. Will turn you a 1v1 monster, combined wirh Sterak's Gage.

Lots of AD with lots of lifesteal. Also gives you a shield before fights.

Another cool lifesteal item. More defensive compared to Bloodthirster.

Do you need a second chance in a fight? Do you need armor? Buy this.

One of the core items in crit build. Good amount of attack speed and some critical hit chance with base movement speed. Plus some damage with its passive to burst.

The other core item in crit build. Huge AD with improved crit damage with crit chance.

Almost every stat and great passives which gives movement speed and improves damage after using a skill. For example, if you use your E and then Q someone squishy, you will deal a great damage.

Defensive alternate to Statikk Shiv. Shield can help a lot and can be bought after selling boots in order to make %100 crit.

Old Stormrazor was better in my opinion. But this works well too. Good base stats and slow in order to stick to the enemy.

Do you want insane damage with tankiness? Combined with Guinsoo's Rageblade, this item actually works surprisingly well with Master Yi.

Defensive option. Grievous wound effect is great against champs like Fiora as it decreases lifesteal.

Main reason is its active which removes CC.

-10.8 (Minor Updates)
-Edited Items.
-Added threats.
-Edited threats.
-Edited runes.
-Added synergies.

-9.23 (Major Updates - RIP Shojin)
-Removed Traditional Master Yi page.
-Edited items.
-Edited runes.
-Edited items chapter.
-Edited runes chapter.
-Edited threats.
-Edited runes chapter.
-Edited skills chapter.

-9.22 (No Updates)
-This patch didn't change your gameplay. (Except some matchups became easier.)

-9.21 (No Updates)
-This patch didn't change your gameplay.

-9.20 (Minor Upsate)
-Edited runes.
-Edited threats.

-9.19 (Minor Update)
-Added more threats.
-Edited threats.

-9.18 (Major Update)
-Added items section.
-Added more threats.
-Edited threats.
-Edited items.
-Edited runes.

-9.6 (Minor Update)
-Added more threats.
-Edited threats.

-9.4 (Major Update)
-Edited About Me chapter.
-Edited Runes chapter.
-Added Jungler Master Yi page.
-Edited My Plans chapter.
-Edited Items.
-Edited Threats.
-Added more threats.

-9.3 (Major Update)
-Edited Items.
-Added more threats.
-Edited About Me chapter.
-Edited Runes. (Notes Actually)
-Added more BBCoding (Thanks Fruxo)
-Edited My Plans chapter.

-9.2 (Minor Update)
-Edited About Me chapter.
-Edited Items (Notes mostly)
-Edited Runes chapter.

-9.1 (Major Update)
-Edited Skills chapter.
-Added more threats and synergies.
-Edited threats.
-Added Traditional Master Yi page.
-Added Runes chapter.
-Edited items.
-Added Spells chapter.
-Added My Plans chapter.
-Corrected some grammar mistakes.
-Edited Spells chapter.
-Edited About Me chapter.

-8.24
-Created guide (or build because the gameplay section wasn't created. It will be created later.).
-Added spells.
-Added items.
-Added runes.
-Added threats.
-Added synergies.
-Added About Me chapter.
-Added About Champion chapter.
-Added Pros chapter.
-Added Cons chapter.
-Added Skills chapter.

-Gameplay section will be created and expand greatly, but process will be sooooo slow. Sorry about that.
-More threats will be added.
-More synergies will be added.
-Notes will be more detailed.
-More BBCoding will be added.

This section is being created. Thanks for your patience and my apologies as I did not create this chapter for around 10 months.