This is a very effective speed/leechlife build for an underestimated champion : Master Yi !

YOU HAVE TO TRY IT !

Pros :

-High Attack Speed = High HPs Regen
-High DPS Output
-High Mobility = High Survability
-If u don't die in 1 burst, you win !
-Build not very expensive
-Very dangerous early in the game
-Very simple to play

-Cons

-Very sensitive to teamfight CC

Red : Greater Mark of Desolation Armor Penetration (maximize damage)
Yellow : Armor (help for jungling)
Blue : Attack speed (main stat)
Purple : Greater Quintessence of Desolation Armor Penetration (maximize damage)

Start : + x3

: Great help for jungling & farming creeps, free ward for map control, nice starting leech life.
: Good for attack speed since you need nothing else.
: Your CORE item, like a 2nd ultimate...
: Life Leech / Attack Speed / Armor Pen. ... Oh yeah Baby ! (can't stand people saying it's not a good item for a Yi, maybe the most interesting gold/output ratio over all other items..)
: OMG HE CAN'T DIE !
: OMG HE BLOCKED MY SPELL WITH 3% HPS !

Than switch for for more damage / life leech

1-

Start your jungling with and x3.

Mini Golems -> Wraith -> Wolves

*Mini Golems : If u proc on your alpha strike, smite on it to take the minus damage possible, at about 2/3 your hps, use your first .
*Wraith : Aim for the big one, try to not use until you are at about 30% hps, ==BE AWARE== when only 2 little wraith left, switch target for your double hit (you'll gain 1 hit).
*Wolves : If u don't proc at all on your alpha strike against Golems & Wraith, you should be about 260-265 hps when you reach wolves. Nothing special to know, aim for the big one.

2-

You just finished wolves and you are currently lvl 3 but with no buff, take a first look at your minimap, it's your first attack window, if u see any low hps enemy keeping pushing, go to finish them off, if not, teleport back.

Wait until u have enough to buy (could be 20-30s long) than back to jungling !

Mini Golems -> Wraith -> Wolves (again)

This time don't use any , smite again on golems. After you finish, you should be lvl 4, this is the 2nd attack windows, look at your map etc... If nothing, TP back again.

3-

Transform your and to than head back for the 2nd part of the jungle

Blue -> Mini Golems -> Wraith -> Red - Wolves

Nothing much to know about it, smite on Blue Golem and Lizard than TP back, use only if needed.

4-

Buy + and Sight Ward. You are now lvl 6, it's one of your top moment ganking so aim for a double lane where enemy is the closest to your tower (advise your mate if needed). ==TAKE YOUR TIME BUT DON'T FAIL YOUR GANK==.

: To reach your target.
: If your target flash out
: Boost damage
: To catch up after flash out or after being crowd controled

So : -> -> ->

==== Next step is up to you, jungling, go gank again etc... ====

- + + is so amazing, with this you don't need nor !
-The greater distance between your prey and the tower, the greater chance you have to kill it
- Solo dragon is easily done after ou get , fast enough to not take any risk.
- Don't forget your . You can ward your enemies buffs or dragon to gain map/gank control.
- Ask your teammates after doing your first red buff (before doing wolves) to let the enemy push, since you'll go gank just about 30s after.
- Your early is really crucial, you NEED to success on the first gank !
- is your main item, try to get it ASAP, when you get it you've reached your power-peak.
- Don't forget . I usually take them for the first time after doing , just before switching my to
- You don't need BF Glaive based items (only to replace ) cause you have enough damage ! & are there to do the job.
- & are there because....... YOU DON'T NEED MORE DAMAGE, with your high ranked leech life and attack speed you can even kill tanks fast enough, so these 2 items are there to unsure that you are safe.
- Don't forget that allows you to IGNORE SNARE.
- If u are focused by an ENEMY TOWER, use your , it'll make you loose aggro ! It'll help you to tower dive non-CC champions too.
- will allow you to DODGE SKILLSHOT CROWD CONTROL like Anivia !
- When using you are nowhere physical.
- LET YOUR MATES ASSIST YOU ON KILLS ! This way they'll not get starved.
- Blue is TOTALLY CRUCIAL for you, you are one of the most mana***** champions in this game.

==== ENJOY and DON'T FORGET to post a comment, but not before trying it ! ====