Want a champion that moves from point A to point B in a flash? Want incredibly high DPS whilst keeping survivability? You want a champion that's fun, epic and has endless possibilities? Look no further than Master Yi!
I've played a lot of Master Yi games as he is my favorite champion in League of Legends. Played him with all the different builds there are. Pure DPS, Abilty Power, Attack Speed, etc. Then, as I leveled up, my favorite use of Master Yi, the pure DPS build, got shut down before I could even get in range of my Alpha Strike and I got focused and hit by CC so much that even Cleanse + Quicksilver Sash + Loads of lifesteal couldn't save my ***. Then, as I knew I was gonna be focused anyway, I thought of a build. The result... Read on to hear more! :D

Let's start by discussing my runes.
As is extremely normal for DPS champions, I use the standard ArP Quints and Marks.
For my Seals, I go with flat armor ones. Sure, a lot of people might take crit chance or attack speed over this, but I don't. As I like to farm early game and maybe steal a jungle or two when my opponents are out of position for a bit (if they're dead or attempting a gank) and these runes help lowering the amount of damage you take early game by quite a bit. I just like the runes as I play on survivability and not pure DPS with Master Yi.
For my Glyphs, I pick Magic Resist per level runes. Since in lanes, you usually won't face an AP champ with a decent burst or any high damage output before leveling up a bit, I prefer these over the flat magic resist runes as they give a bit more of an edge mid/late game, where magic resist becomes more of a mandate than a luxury.

My Masteries are pretty standard. Improved Ghost and Exhaust are the most important ones though, as I like those Summoner Spells on Master Yi, having a slightly improved version of them never hurts. Feel free to mix this up to like a 1-21-8 or whatever Mastery Tree you want. I just like the way mine are distributed.

R > E > Q > W
Follow this mostly though if you're being harassed a bit too much early game or you have to go mid, despite not being an AP Yi, feel free to pick up a point or two in W earlier. It's really helpful early game as the minion focus could screw you over after you beat a camp and have like half a bar of life left. It feels so good to Meditate and heal up a bit and NOT die to minion focus and get some early kills.

Why do I use Ghost and Exhaust? Well, I don't use these ALL the time. Really, this is just the perfect oppurtunity build. I prefer using these, but sometimes I use Flash, Cleanse or hell, even Ignite if I'm going AP Yi or if I know I'm gonna go mid for some reason. Just pick between Ghost, Exhaust, Flash and Cleanse and you'll be fine on summoner spells most of the time.

Ah yes, the items. These are going to need some explanation as this isn't your every day Yi build.
I like to start of by buying Boots of Speed and 3 health potions. The health potions help sustain your survivability and laning prowess without having you waste a lot of mana on Meditate. I get the Boots of Speed just so I'm a bit faster and go last hit minions a bit easier whilst staying out of the enemy's range a lot easier. Upgrade these to situational boots. I choose the Berserker's Greaves most of the time but if the enemy is rocking a lot of CC, has a lot of casters or has a lot of DPS in their team, feel free to pick up Mercury's Threads or Ninja Tabi instead.
Immediately after your boots, go for Youmuu's Ghostblade. Get The Brutalizer first. The extra ArP from it makes you deal true damage to just about anyone on the opposing team at this point and it gives you some much appreciated CDR. The most important about Youmuu's is definitely the active. More movement speed next to Ghost and Highlander? Yes please! More attack speed and hitting the enemy for increased duration of the whole thing? Yes please! If you get Youmuu's and don't use the active to initiate, you might as well not get it. You can roam the map and catch a lot of people off guard with the incredible movement speed. Even if they attempt to escape, if you have Ghost, Highlander AND Alpha Strike, they are going to need a damn good escape route.
Now this 3rd item slot is a lot more open. I just put in Wit's End there as that is what I usually take. The enemy has a decent AP champ most of the time so the magic resist helps a ton. So does the attack speed. What you should do after you have Wit's End and you want to assassinate a heavy AP champ on the opponent's team. Come out of a brush with Youmuu's active maybe even Highlander and Alpha Strike locked on the opponent. You will usually catch them before they can hit you with their stun or whatever due to the insane speed at which you are approaching them. Then, you auto attack them from close range and get some magic resist stacks from this item's passive. If you got this far, the enemy will likely not be able to burts you down in one go at this point so just to take him out VERY quickly.
My preferred item for this slot is another one though it isn't really advised if the enemy has some decent AP burst damage on their side. What is this item that gives you the much appreciated attack speed? Is it a Phantom Dancer? No. It is the almighty Sword of the Divine! If you get this item and combine the active ability with the Youmuu's active and Highlander, you just cut down enemies in a matter of seconds. Sword of the Divine's active is also a great target for champions like Jax and Sivir. They can't dodge, you have added ArP, you have sick attack speed and movement speed, ETC! The best part? ArP from runes, Youmuu's AND Sword of the Divine. If you've been a little fed in the early game, then you SHOULD be dealing true damage or damn close to true damage to your opponents. Enemies usually like to get a good magic resist item against a balanced team so you'll likely only not deal true damage to their tank/tanky DPS. Still, the ArP is much appreciated and the damage you deal because of it is just awesome.
Why not a Phandom Dancer in the 3rd spot? It's quite a bit more expensive, you get movement speed from Youmuu's, you don't really need the crit chance. I mean, it'd help, but I don't want to give out so much gold on a bit of crit chance on an already expensive build.
Item number 4, the almighty Frozen Mallet! I would agree that this item is too expensive for what it does, but for this build, it is pretty much a mandate. Some attack damage, slowing on hit, increased survivability. It's so funny to see an enemy struggling to move forward if you got a red buff and a Frozen Mallet. It's simply great for picking up some kills.
Now, item number 5. After this item, you will likely not deal too much damage to the opponents because this and the Frozen Mallet are incredibly expensive. The upside? You probably won't die a whole lot in this game anymore. That's it really, this item is simply a set-up for the 6th and final item for this build.
The final, and MOST IMPORTANT slot of this build goes to the Atma's Impaler. Sure, a champion like Jarvan or Xin Zhao make a bit better use of it but in this build, with over 3,5k HP, you don't die, you don't miss, you move incredibly fast, you have some damn good ArP, crazy attack speed and with the Atma's, some half decent attack damage. No can escape from you. If someone separates from the pack for about 10 seconds, it's plenty for you to run in, rape and get out. It's just awesome, I love using this build and in the rare occasion that I get this item, it's just so much fun to put it to great use!

Now, if you were able to complete this build, here's how you should handle this type of Master Yi. The golden rule is to ALWAYS, and I mean ALWAYS use your item actives and Highlander the moment a team fight starts. You don't die as easy as most Yi's and people will probably focus you. If they do, hit a bit before running if you get in danger of dying. If they don't focus you because they see 3k+ HP on you, then it's your time to shine. Get in there with Alpha Strike, run with incredibly high speeds to the biggest threats in your enemy team and dish out TONS of damage. Impressive ArP with decent AD, awesome attack speed and some great actives on you whilst being pretty damn hard to kill is a royal pain in the butt for the enemy team. The great thing about it? They can't do **** to you. Fights are initiated by tanks and their CC skills, and your casters dealing MASSIVE damage with their bursts. Your job starts right then and there. You see you're casters beginning their burst. You activate Highlander, Youmuu's and Sword of the Divine if you hae it and go in with Alpha Strike. By the time the Alpha Strike animation ends, your casters should be done or hitting their final skill. The enemy team will likely have 1 or 2, if not more people who are near death. Since they most likely used their CC like stuns in the teamfight, you can rush after them and take them out without any real problems. That is how it SHOULD go. It's not always like that but you have to try and shape the situation for yourself anyway.

This has been too much talk so let's just move on to the summary of this guide.

Let's go over the important parts of this guide.

Runes: The ArP runes are a mandate, the seals and glyphs are mostly up to preference.
Summoner Skills: Mostly preference but Ghost, Exhaust, Flash and Cleanse are by far the superior options on Master Yi.
Items: The core is Youmuu's, Frozen Mallet, Warmog's and Atma's. It's 4 spots and boots are a mandate so really, you only have 1 spot and that is mostly situational though I prefer SotD or Wit's End.
Masteries: Purely up to preference. You could go 0 - 21 - 9 or 21 - 0 - 9 or whatever.
Skill Sequence: Mostly Wuju Style and Alpha Strike though a situational Meditate never hurts your overal performance by any real amount.

That was it. I hope you'll try the build out. I personally love this build and it works out pretty decently. Please try the build out before rating negatively as it's not as bad as it may look for a Master Yi!