Welcome to my first (so it will probably be terribad) build guide for Master Yi, The Wuju Bladesman!

Master Yi is one my favorite champions, and even if he gets difficult to play the higher ELO and the higher Division you are in, he is still loads of fun to play. This guide will mainly be Jungle oriented, since he can destroy people and snowball extremely hard if played correctly. He excels at 1v1's and despite his lack of crowd control, he is still a massive threat to any team.

Without further a do (until I get called out for a bad introduction), let's get started!

Pros
+His Q is wonderful at wave clear and jungling, as well as dodging skillshots
+Meditate is an extremely effective heal, even if you don't max it first.
+Unlike other jungles (cough cough Pantheon cough cough), blue buff is not a massive priority due to his E.
+Speaking of Pantheon, he has the highest base movement speed in the game
+Highlander has an extremely low cooldown and renders many champions slows useless when activated.
+Once his ult has been upgraded, champion kills and assists almost reset cooldowns on all basic abiltiies.
+E's true damage

Cons
-A bit mana dependent early on
-His Q and W are channeled, meaning he can't "move" for a few seconds (Alpha Strike can displace you, but you cannot control what you hit)
-Absolutely zero crowd control
-Squishy even with Meditate
-Cooldowns on basic abilities are long
-Limited to Top Lane and Jungle unless the player is very skilled at Melee vs. Ranged Matchups

Fury because your kit relies on your attack speed, and Q's cooldown is lowered each time a basic attack hits.
Double-Edged Sword or Feast. It's mostly personal preference, but I prefer Feast over the Sword since Yi is already squishy enough.
Vampirism. I've had negative effects on Natural Talent, and since Yi is fairly squishy, Lifesteal helps a lot.
Bounty Hunter OR Oppressor. This is one that's entirely based on what your team comp is. If you have a lot of CC, I would go Oppressor. If you don't, go Bounty Hunter. Since Yi has no CC at all, I prefer Bounty Hunter, but I've had success with Oppressor.
Battering Blows. Fairly obvious. Yi is no longer an AP God.
Warlord's Bloodlust OR Fervor of Battle. Even though Deathfire Touch is a good (overpowered, IMO) mastery, I feel it's better for champions such as Malzahar and Brand who have DoT abilities naturally. Since my personal build includes Infinity Edge and Statikk Shiv, I sometimes go Warlord's Bloodlust for the extra healing. But sometimes, I like going Fervor of Battle. Honestly? It's all down to personal preference. Your choice :D.

Wanderer OR Savagery. Also personal preference. Since I don't trust my attention sometimes, I prefer Savagery, but Wanderer is also viable for ganking.
Runic Affinity. I've had little success with Secret Stash on Master Yi, as I use Refillable Potions over Potions. As well, the extra long buffs are useful when it comes to Blue Buff.
Merciless. Merciless makes picking off weak Jinx's even easier, and making multi kills more and more prevalent. I feel like Meditation just doesn't give back enough Mana in my taste, but everyone is different.
Dangerous Game. Yi is primarily a Top Lane and Jungle champion, meaning you are rarely with other players unless you are ganking or pushing.

Items are perhaps the most controversial part of any build, so let's get into it straight away.

For me, this is what I prioritize as Master Yi:
-Attack Speed to 1.95-2.0
-Attack Damage + Lifesteal (Bloodthrister and Infinity Edge work the best)
-Defenses (As shown above in my item set)

Why? Because with Attack Speed, your passive is used more often, your Q is continiuously getting lower cooldowns, and enemies die more! I usually get Devourer, Statikk Shiv, and Bezserker Greave's to get my Attack Speed up to around 1.9-2.0 Attack Speed. I don't go any higher since my ult maxes my Attack Speed and I would have a signficiant lack of damage going into the attacks and low lifesteal, making 1v1's harder.

Speaking of damage, I get two damage items: Bloodthirster and Infinity Edge. Yes, these are expensive. Yes, these rely on a LOT of snowballing. But with such a high attack speed, you can clear waves and jungle camps extremely fast, making your gold generation extremely high. In addition, the Attack Speed pairs well with his Q and passive, so assassinating innocent enemy champions means your gold generation goes up even higher. As long as you don't get cocky, it is pretty fast to get these.

Lastly, I get one defensive/offensive item. Since this is usually late game, I build based on the other teams composition. Lots of crowd control? Merc Scimitar. Lot's of AP Burst? Maw of Malmortius. Lot's of AD? Dead Man's Plate/Thornmail. Lots of Burst? Death's Dance. Generally, it's all down to preference. I usually have success with these items in particular.

The general order of Yi Skill levelling is...
R < Q < E < W

Start Q first, as this will do damage to nearby jungle minions as well as save your hide from getting ganked or a devastating skillshot.

At Level 2, either start W or E. If you don't have much experience Jungling or you don't have many runes or masteries, start W. If you do have runes and masteries, start E.

The key to W is to use it whenever you are low in the Jungle. The heal effect is stronger the lower health you are, and since it reduces damage taken, you can use it after or during a jungle camp. It's an incredible useful ability but since you are a mobile assassin, this heal ability renders you motionless, so it's better to use it to wait for cooldowns and to finish a burst.

E is a tank shredder. That's basically it. It gives you a passive of 10% bonus AD. When you activate it, you deal 10/15/20/25/30 True Damage per hit, with +(.1/.125/.15/.175/.2 AD) in bonus. This is EXTREMELY effective when you are trying to burst a tank, as the True Damage ignores Armor and Magic Resistance. Your only problem is if the Tank has extremely high health, but that's mild when your attack speed is at 2.5 and your movement speed is extremely fast.

Your Ult, Highlander, is a life savior and kill confirmer. It boosts your Attack Speed by 30/55/80% and your Movement Speed by 25/35/45% for 10 seconds. What makes this ult so gosh darn good is the extremely low cooldown (1:15 minutes) and the fact that every kill and assist while it is active extends the duration by 4 seconds. Oh yeah, you are also immune to slows. So you can go in, assassinate whoever you want, and run! OR you can stay and slaughter the entire team (PENTAKILL). Either way, this ult is something you can spam without much worry. Just be cautious that you are still susceptible to disables.

When starting Dragon side, (bot lane has Red), I go Krugs > Raptors > Red Buff > Bot Crab. Depending on the situation, I either gank Mid or Bot. If they don't need to be ganked, I go to Wolves > Blue Buff > Gromp (Praise Be Unto Him) > Top Crab. From there I usually roam or return to jungling.

Before the camps spawn, I ask my Top Laner to ward my Blue Buff while I ward theirs. This is so if I get invaded I can invade back and it ends up even. It's risky, but it can make a big difference and can confuse the opponent.

IF YOU DECIDE TO INVADE, TAKE ONLY THEIR RED OR BLUE BUFF RESPECTIVELY.

Note: I have not had much experience double jungling, so I will not mention it until I learn more about it. Apologies.

If your team wants to snowball you hard, they are good teammates. Generally, have them try to bait them into a sandwich where you can sneak behind them and snipe the ADC and Mid laner before your team dies. This is a common strategy and risky, but it often works. If you are forced to confront them head on, get your tankiest player to bait out crowd control spells and then ult and Q onto their ADC or Mage, whichever one is more dangerous. Assuming this fight is where you have an Attack Speed of 1.9-2.0 and at least one damage item, it should be easy to kill them as long as they are not focusing you. If you get focused, keep attacking and Q whenever possible, as you probably won't be able to escape the high burst of an ADC and Mage combined.

Until I get loads more clips of teamfights, I will update this as time goes on.