Hai guys.
I really love Yi due to his awesome damage, chasing, escaping and farming potential. But there was a big problem: playing this standard AD/AS build on him never really worked for me. This was due to 2 facts:

1. Yi has no CC.
2. All this Offtanks and everything else that can stun bursted me to hell before I even got near to them.

So my thoughts were: "this sucks."
A week ago (from writing this guide) I just picked Yi as an instalock. Was just an... call it intuition. I wanted to try an Offtank build on him as Yi already has great damage output even without a lot of damage items.
I played more and more games with that after having surprisingly sucess with it in the first game. And ffs - it works! For me actually. Hopefully for you as well ;)

I will keep this guide relatively short (comparing to my Lanewick-Guide) since I don't have that much time at the moment. I'm sry for that and I will try to add more and more aspects by the time. But as I believe you guys out there are all more or less good players you should be able to play my build even without 10 pages of description :) Even though I personally love to read long comprehensive guides, too...

This is kinda op.
You just ****ing jump with Alpha Strike to an enemy, activate Highlander and Wuju Style and rape him without letting him a chance to escape. In best case you don't even Alpha Strike - this is possible by hiding in a bush and running out quickly as soon as the enemy overextends. Then you can also close a possible gap with Alpha Strike again.

Yi has one big problem in this meta: he falls quickly 'cause he's ****ing squishy and has actually NO CC. Even though he's a melee.
On the other hand Yi is - theoretically - a great countercarry. He can jump to any champion without getting touched and his damage and movement speed is ****ing awesome. No squishy can stand that. Except... he can "jump" away or stun you (like Cait, Ashe, Tristana, Vayne... every ****ing ranged??). So what Yi needs is a slow (since he has no stun). And Frozen Mallet offers you exactly what you need: no more squishyness, still damage (especially since Yi's base damage is SO ****ING HUGE with that op Wuju Style) and 24/7 slow.
Now add a Atma's Impaler to this and you get a ****ing Offtank, 24/7 and roflcopter damage.
Add a Wit's End and you are op.

So what's so awesome about Yi?
Well, there are a lot of things: like his fantastic jump and his funny Meditate.
But just from the objective side of view it's (beside these also awesome skills) his Wuju Style. This Style is what makes him so ****ing strong and let him rape EVERY comparable champion at low levels. His base damage is just awesome. I mean, seriously: in mid you have + 70 dmg by activating it! Like a bonus B. F. Sword + Pickaxe! I mean, just imagine a carry would get at level 9 an extra B. F. Sword + Pickaxe...
Just don't forget to activate it.

You maybe think now, "wait, so Yi got high damage - why not buying some more AS early on?"
I can tell you, Yi doesn't need. Highlander is far enough. Remember: it's cooldown is resetted everytime you get a kill! So in best case Highlander is never or at least just a few times on cooldown.

You got now why I love Yi?

We start with boots to be able to keep the distance to our enemys low or to be able to escape. Also the healthpots allow a great early game and together with Teleport you can hold nearly every lane.

Wriggle's Lantern is just a great item itself. You have always this ward + you can do dragon and baron just that fast. Especially with Yi. Just use Highlander and Wuju Style and rape this dragon in like a few seconds! :) I also love the lifesteal on Yi. The armor is also nice, but not the main point about this item.

Mercury's Treads are in my opinion a have-to on Yi. You are so vulnerable to stuns. Slow's don't matter when using your Highlander, but every stun hurts. Also the MR is very useful.

Frozen Mallet should be clear now ;) Just op on Yi. And please don't tell me you would lack on damage, I wouldn't believe you. Remember Wuju Style.

Atma's Impaler is just op. So much damage, so great defense. Get the Chain Vest early on if you have problems with an physical based champion in lane.

Wit's End just rounds this up. Most times I don't get to this item (or just to Recurve Bow), but when you finish it, the games is over so to say. Your damage increases again a lot and also your defense does. You're now a complete and great countercarry offtank!

What to buy after finishing this build?

Well, buy whatever fit's in the situation. At the latest when grabbing Atma's Impaler you are no longer bound to this build and should build whatever you need to dominate your enemys.
e.g.:
Banshee's Veil versus burst damage mages.
Madred's Bloodrazor versus high amounts of HP.
Hexdrinker/ Wit's End versus DoT mages.

Hmm. As he's more or less an Offtank with this build you can take solo top with him. But when there is a hardcounter on the enemys solo top (like Jarvan IV, Nasus, Lee Sin) you probably shouldn't go there.
There is also the possibility to go bottom as a counterlane (as already mentioned Yi is great at countering ranged carrys) or you can also jungle with this build. Just get the Cloth Armor + 5x Healthpot first and switch Teleport to Smite. Then continue just with the normal build.

Nope.
There are 2 good reasons to take Teleport on Yi:

1. You can hold easily most lanes. Yi can push/clear creeps quite good with Alpha Strike and Wuju Style and adding Teleport to this makes him extremely hard to get away from his lane.
2. Yi is such a great backdoor/splitpushing champion. You can smash every tower in a few seconds with the op Wuju Style and Highlander combination. Teleport makes him even greater. If you become useless in a teamfight for some reason (e.g. fed AP carry or something like that) or the teams are just chilling around or the enemys are doing baron - just port to a pushing creepwave and clear some towers!

Of course this is just an option. It's just my opinion Teleport is such great on Yi. If you think different, feel free to kick Teleport for something else - I also ran a few times with Exhaust instead to get already a slow in early game (if grabbing Exhaust you really need to skill Wuju Style first! Early kill is sure then - just op).

What you shouldn't grab:

Ghost - Highlander for noobs?
Fortity - wtf?
Revive - WTF???
Ignite - I really don't think Ignite is viable on Yi. Exhaust is way stronger...

I put the first point in Alpha Strike to have on the one hand a gap closer and on the other hand something like a "defense". Alpha Strike allows me to get invulnerable for a few seconds and as Yi is very squishy at the beginning this can be very helpful.
As already mentioned the "place" of your first skillpoint is regulated by your summoner spells or at least by the first one (since Flash is a must-have). If you can compensate your early weakness with that summoner skill, Wuju Style is viable.

In teamfights Yi should constantly harass enemy's squishies who chill around a bit behind. You can get to them easily with Alpha Strike AS SOON AS THE FIGHT IS INITIATED. Don't go in there before! They would focus you and you would die without dealing damage.
But as soon as the fight starts, it will be hard for them to focus you. Especially since you're invulnerable for like a second due to Alpha Strike and noone really KNOWS where you will end at. This is what makes Yi such a great countercarry.

Maybe some of you thought so far the slow by Frozen Mallet is not needed as Yi is very fast with Highlander and can catch up a lot of enemys by himself.
But even when we don't expect enemys to have a skill to escape you (by jumping over a wall for example), the slow is still useful.
Imagine the following situation:
You are Master Yi and chasing a Ashe who already finished her Phantom Dancer with Highlander.
Now her movement speed is also quite high. I don't want to calculate exact values here, but see this: everytime Yi is close enough to attack and attack her, Ashe will keep running. This results in a gap between both. Yi now has to run a short time again to get close enough to do the next attack and again a gap is created.
Attack Speed makes this gap a bit closer by carrying out the attack faster.
Now imagine you chase her in the same situation, but with Frozen Mallet. Every time you are close enough to do an attack, the creating gap is very close as Ashe's movement speed is VERY low. Including the small attack range every champion has Yi is now able to do nearly every autoattack he could do versus a staying enemy even when chasing.

Meditate can be a great tank spell depending on your enemys and the right use of it.
First of all: when the enemys have champions like Pantheon, Taric, Singed, Leona etc. who can stun you right away, this skill is more or less useless in teamfights. OTHERWISE you are able to even tank a whole team with your Meditate by using Alpha Strike to initiate.
Meditate is also useful versus some other special skills.
Use it versus...
Requiem
Ace in the Hole
Trueshot Barrage
Undying Rage - not that obvious, but imagine you smash Tryndamere and he uses his ultimate but you're already quite low. By activating Meditate he either way has to run (and you can chase him) or to try to kill you (what's more or less impossible).
Javelin Toss / Takedown

Actually mobafire is not adding the damage of Atma's Impaler at the top of the guide.
Also Wuju Style is (of course) not included.
The 153 damage are at level 18 circa 205 damage with Atma's.
When Wuju Style's passive is active, you have 240 damage, by activating it 275. There is really no lack of damage when playing Yi ;)

So that's it for now.
As promised I will try to write some more by the time.
****ing real life...
Tell me in the comments how you did with this build and send me a Screenshot with your stats :)

CellOne out.