Hello, my name is Murphy (Void of Sleep) and this is my first guide for League of Legends. Instead of putting in a bunch of pictures and making it pleasant to see, I shall make this guide to be quickly read and then utilized. As such, this requires basic knowledge of Yi's skillset. I have played Master Yi off and on for a few months now and if you couldn't get mid with him, he's was always a weak choice. Now with the rework, Yi is no longer a wannabe Kassadin, but a viable choice in any match.

Pros:

Great Chaser
Easy to Learn
Can Shutdown Carries
Strong Ganker
Hard to Lockdown
Perfect Assassin
Great Counter-Jungler
Powerful Dueler
Fast At Clearing Jungle
Amazing Split Pusher

Cons:
Low HP pool
No Hard CC
Weak Teamfights

The cons are not many, but they are a problem if you are laning, but playing Assassin Yi should be no real problem.

Take Smite when jungling, because if you don't, you're shouldn't be jungling. Your secondary spell can be whatever floats your boat, really. Don't take revive, because you shouldn't be feeding, and don't take Clairvoyance or Clarity because you shouldn't be having mana problems with blue buff and you're not a support. I tend to choose TELEPORT!! Why, you ask, and not flash or Ghost? Well, with the movespeed from your items and your ult, Yi should already be catching everyone easily. Also, Flash at your enemy, what do they do? Flash further. No distance was closed in that chase. Also, you're Q and proper sight (use a ward where you know enemies will be) will allow you to jump walls. There has been many times my team will be laying siege to the enemy base and one of theirs will get too close to the wall. With one click, I am in their base softening them up while my team takes the turret. Teleport allows more crazy maneuvers than Flash or Ghost. I'll explain more later.

You may not agree with my item build, but hear me out. Ever been playing AD and have a Dr. PWNDO with five Warmogs and a Ninja Tabi comes out of the fog and you just stop him? With Yi and Blade of the Ruined King, you can! Yi's passive allows him to strike twice every fourth consecutive attack. With BRK, that is 25% of their current health, not even including crits and AD! Also, the sustain from BRK will help dramatically, between that and your W, you should never be caught with low HP in the jungle or in transit. Black Cleaver gives much needed HP and a nice boost to AD. The real beauty is with Yi's new passive, going 1v1 with someone means they will have a fourth of their armor gone, leaving them open to your devastating crits. Ever have someone run away with low HP and your ignite didn't cut it, or maybe you forgot it? Not with the Spirit of the Elder Lizard. While losing no jungle power, you always have the Red Buff for leaving none alive and helping in your dueling. Static Shiv gives great boosts and the AoE lightning helps with teamfights and creep clearing. Lasly, I.E. for those wicked crits and boost to AD.

This is a reminder (or if you didn't know, you're gonna learn) for those who truely utilize Master Yi's Q and why is he is a great Assassin. If you target a creep with Alpha Strike just RIGHT BEFORE it dies, I mean, when you see the killing blow coming for it and it's almost there, Yi will not move, but still dash in and do damage. He will simply return to the spot he activated it at. That means, no putting yourself in danger and being able to hit three enemies (Don't quote me, but I think the creep that was killed before you got there still counts as one of the four attacks). You never have to leave the safety of a turrent or run out of a bush to hit them hard. Don't forgot, Alpha Strike offers you invincibility. While dashing about, Yi is untargetable and can't be hurt. Master this, and you Master Yi. .

When jungling with Master Yi, you're doing less jungle and more gank. Kind of like Shaco. When you are ready to jungle go Blue Buff, Wolves, Wraiths, Red Buff, Golems on your side, and than go for a gank. Look for overextended lanes. If none look safe to gank, clear your wolves and wraiths and then look again. Repeat the process until one of your allies fall below 60% HP, an enemy overextends, or someone is out of place and in a vulnerable position. If below level 6, start with Alpha Strike. If they are alone and too far out for help, hit Wuju Style and beat them back right after you hit them with Alpha Strike. If they are able to be helped by teammates, Alpha Strike a creep near them. Usually, you will hit them and you won't appear next to them to be CC'd to oblivion. If Lv. 6 and higher, start with Master Yi's ult for an easier catch and destroy.

Now this part is taboo, but DO NOT TAKE MINION TAX. You are expected to gank and if you can help it, don't rob your teammates of CS. You have jungle camps to clear anyway, no time to be a douche.

Every game comes down to one thing and that's teamwork. Yi is said to be weak at teamfights and that is true, but that doesn't mean he is weak for the team. Have your team ward their lanes. You can teleport to the wards for game changing plays. For example, let's say you ganked top, got hurt, and bot lane needs you that instant. Looks bad, eh? Not with Yi and Teleport. Just run into the bush, Meditate, and Tele down to bot lane's ward (which should be in a bush as well). The enemy expects that you are still near top lane and will not expect your ult and Alpha Strike from the bushes next to them. Work with your team to surprise your enemy with your assassinations.

That is the end of my guide. I hope it works for you and sorry for the ugly blocks of text. Perhaps I will update this guide to be more eye friendly, perhaps not. Please leave feedback. Any feedback, whether positive or negative, is good feedback.