Very detailed build and for that I appreciate it greatly. I wish it were less of a wall of text though and more graphics. A visual update to this guide would be much appreciated!

Good luck! :)

You can theory-craft all day about how you could own this dps or kite that tank etc. I used Tryn because it's the most obvious example. "Squishies" like Teemo or Kennen or Trist will have no problems against you. Because the fact remains that your build does not maximise Yi's dps protential AND lack survivability. Maybe you do have a good time owning squishies around your level. That does not mean your build will continue to own further up the ladder.

Like you said, your build is for team fights. By the time you complete your build, all fights will be 5v5. A squishy Yi that can kill another squishy in 5 seconds is definitely not very useful there. Unless you're talking about waiting till all the AOE's and CC are gone and you dive in for the KS.

I hope you're not posting the build here to educate, as you don't seem to be open to negative comments. Your build can be improved only if you listen. I know I can't make you but next time you play against a decked out Tryn/Teemo/Xin/Kennen/Swain/Malp/Cho/Kayle etc etc, think about what you can do to "carry" your team.

*hint: gunblade is for ganking loners. I'd get it early or not get it at all.

I like your idea, I can't find you in game however so I guess you are playing on America server.

Hopefully I am mistaken though

@mcaay
It's nice to get some feedback from you, I've used your build before. I thoroughly enjoyed it because it had such high DPS and lifesteal. I really couldn't use it much, because I couldn't get consistent kills in the beginning so my item development was really lacking. I understand the term "Hard Carry", but when I play with a bunch of random people, they're always so surrender-happy. That being said, I must decline you Yi Vs. Yi Challenge, as I don't really build him for 1v1. I would however, love to compare in a few games as allies. My ign is my name here.

@Sonobody
Seriously? You're going to use Tryndamere as an example of squishy? He has got to be the hardest LOW-HEALTH character there is. On top of not being able to die, he gets strong with the less health he has? Duh he's going to rape your face off. Assuming he doesn't have his ult ready though, and you do sneak up on him, with a reasonable gap in health (I'd say about 10%), if you get first strike, you can take him down. If you read the build at all, you don't take someone head on at full health unless you know you're going to destroy them. Your job is not to pop out of nowhere, take down champions randomly that don't help the team, get a good KD ratio, and say the rest of your team sucks. This build was meant as a consistent means to at least be at the economic/experience level of your opponents, and to support the team as a whole. You should NEVER be alone in a position where the enemy team can even get close to you. And if you see Malphite or Cho coming, run. If you can't even do that, then you have no business posting here.

2k health IS a big down side
Downing a squishy in 5 seconds? That'll work assuming the squishy isn't hitting you. A typical endgame Tryn would drain that 2k with 2 crits. Not to mention having to survive the tanks charging around, like Malphite doing 1k burst or Cho starting off with a big bite. You're most likely to be spending your first 5 seconds healing off those wounds.
Defensive masteries wouldn't help you much there. As 4% means it takes 80 extra damage to take you down, that's not likely to save you at level 18. If your aim is to take down their dps before they do that to you, full damage spec plus a survival item (like banshee or extra life steal) is the way to go.

I really disagree with most things you wrote, your thinking is correct but assumptions aren't, so result can't be good. However, as you asked, I didn't give you -1 for this guide. I challenge you to a 1 vs 1. Yi vs Yi, twisted treeline map, we build our yis exactly how our guides say.

Do you accept the challenge?

P.S. Region Europe

Wow 500 views and this many ratings? I'm not arguing with the text. I'll give it +1.

That's true, and thanks for bringing this up, I'll edit this later in the build:
What Mobdafire doesn't calculate correctly is Yi's MR. So, you get 22.5 more MR, with the total coming out to 65.91. NOW, something I don't talk about a lot is lrn2W. Learn to use meditate at an instant's notice. Should you run into a nuke, that can deal significant damage to you across map with warning, like Karthus or Lux, even, Ezreal and Ashe, pop meditate asap. It has to be one of the best nuke defenses in the game. At level 5 you gain an instantaneous 300 Armor and MR? Tanks only wish they could. Coupled with your 65.91, you have about 366 MR against attacks such as Requiem and Finales Funkeln. For the lulz, let's see what Karthus, Lux, Ezreal and Ashe all do with 500 AP and 50% MagPen when you're getting your meditate on:

Lux's ultimate: 327
Ashe's ultimate: 389
Ezreal's ultimate: 389
Karthus' ultimate: 319

Damages were rounded up. Now, this is in the worst case scenario in EVERY way. Your opponent SOMEHOW has 500 AP. Which would require about 4 Zhonya's rings, or 20 stacks on Mejai's Soulstealer and about 2.6 Zhonya's rings. If you play right, this should never happen. If it does, you're pretty screwed. Go and kill them, even if it means your own life, because you can get rid of their stacks. Also, don't forget, this is assuming they have 50% MagPen. You can't actually get 50%, the most you can get with three items is 40% + 40. You can get more, but I'm pretty sure no one stacks Sorcerer's shoes. Anyways, assuming they do that 40% + 40, it is exactly 50% if you have 400 MR. With our MR of 366, with those three items, they would penetrate about 51%, so it's just about dead on.

So if you keep track of items, there's a very specific build they have to follow:
Sorc. Shoes
Void Staff
Haunting Guise
2x Zhonya's ring
Mejai's Soulstealer OR 3rd Zhonya's ring.

And that means.......SQUISHY! Kill em' dead, it should not take more than 4 hits, as they are all pretty squishy without any armor buff.

So all in all, assuming they have ALL the right items, and you have NO items at level 18, you can reduce any of these champ's ult's to under 400 damage, just 20% of your health, WHILE giving yourself 700 hp, 35% of your health.

I see where you're coming from, but for this build, LS is your defense. You should generally be only hitting squishies, with no more than 100 armor. Your DPS would be about 450, and assuming the target has full health at 2500(worst case scenario), then it will take roughly 5.5 seconds to bring them down. Of during which time, you'll be making about 180 health per hit. Basically, you would be screwed if you sustained about 2500 in two seconds, which isn't a scenario you should put yourself in anyway. If you wanted to add health, I suggest Walrog's armor, but that's for a team fighting Yi.

Though I do see where you're coming from, and the most irritating tank that comes to mind is Rammus. His roll, taunt, and passive abilities really piss me off to no end in a game, and especially during late game, your team may have a 4v5 problem where you can't pick people off. But as I suggested, it's best to have your team defend while you go off on your own, being a distraction in those situations.

wow great build +1

agreed but if you get 2 lifesteal items and bust your ult Yi is good at keeping his health up in a fight. just need to avoid ap nukes. in general nice build.

Build looks good, only thing might be more health, seeing how 2k might not be enough in the later game when some tanks might be able to hit you hard.