Master Yi is a little-seen champion these days, as melee carries are greatly outclassed by their ranged counterparts. However, in the jungle, he has excellent clear times, high damage potential and the ability to seriously harm enemies who overextend. Late-game, he is very strong for assassinating squishy targets, cleaning up teamfights, or backdooring. But mostly, he's really fun to play.

This guide is still a work in progress, so feedback is appreciated

The item choices shown are just a basic outline, and you'll rarely actually find this to be the exact optimal build. Remember to switch up your items based on your needs. The reasons behind each item shown are given below:

Machete + Pots: This is the basic start for every jungler. If you enjoy living dangerously, you could try to vary it up - for example, getting Cloth Armor so you can rush Ninja Tabi, or even getting something like Boots or Dagger first. This is risky, but the basic Machete start is very very safe, and you'll probably end up with about half your pots left over by your first recall, so consider substituting some for mana pots.

Avarice Blade: This item gives you additional gold income, which will help you get your endgame build a bit faster. The crit chance also works well with your Wuju Style. Mostly, though, it's for the cash and late-game Atma's.

Ninja Tabi: These make you take less damage in the jungle and when fighting the enemy ADC or bruiser. If necessary, replace with Mercury's Treads.

Vampiric Scepter: Now that you've got good jungle clear time and some armor, you want Lifesteal so you can survive the jungle camps even better.

Giant's Belt into Warmogs: By now, you're going to need to get some tankiness on you. Warmog's Armor is the best item for this. Once you get it, you'll have a much easier time staying alive in fights.

Phantom Dancer: The classic Yi item, it gives attack speed, crit chance, and movement speed.

Infinity Edge: With all the crit chance you already have, this item will be granting crazy amounts of damage, letting you shred squishy targets with impunity.

Bloodthirster: Now, not only do you have crazy damage, you also regain health as long as you're fighting. You should win most duels easily with this item.

Atma's Impaler: Armor works well with the health from Warmog's, Crit Chance helps your damage, and the bonus AD is quite useful too. It also builds out of that early Avirice Blade, which is nice.

Now, Master Yi has precisely zero forms of CC, which makes his ganks rather questionable. To make up for this, you have 2 things:

A) Alpha Strike is a strong gap-closer that can deal a signifigant amount of damage early on. Use it to chase enemies who are low on health.

B) Teleport can also be used to gank. Ask your teammates to lay down wards in their bushes, so you retain the element of surprise. Try to time your teleports so that you land when the enemy is between you and your tower, so they have a harder time escaping.