Team 1 = Laning
Build 1 = Standard
Build 2 = Defensive; recomended if you are still a noob or starting with Lee Sin

Team 2 = Jungling
Build 1 = Recommended if have no experience jungling; uses smite
Build 2 = Recomended if you are used to jungle; uses no smite


Hi there! This is my first build, where I try to do more than an item list, but also offer some tips and tricks on the fourth ninja in the league, Lee Sin.
I would like to thank the players Jazzzmine and Kapziel of the EU servers for helping me making the movies in this guide.
You can find me with the nick KABOOOMM at EU servers.
Feel free to rate and comment.

Pros:
+Nice DPS
+Good chaser
+He has 7 abilities and none of them is useless
+Two of them are dash-like movements (he's a ninja, damn!)
+Two of them can reveal hidden enemies
+He is a ninja! (using energy instead of mana makes your abilities much more spammable)

Cons:
-Kinda squishy when facing hand-to-hand combat
-His nukes don't hit for a lot (excepting his ultimate, but that one isn't as spammable as the others)
-He can be a good farmer, but only if you know how to properly use his passive Flurry

Greater Mark of DesolationGreater Quintessence of Desolation Armor penetration marks and quints as this ninja is an assassin.
Dodge Seals because he has lot of hand-to-hand combat.
Cooldown reduction (CDR) glyphs make his abilities more spammable.

If you don't feel confortable on jungling, Flat Health Quintessences can help you, but I tend to dislike them a bit since they were nerfed :(

Most builds on Lee Sin don't pick Archaic Knowledge, but I must remind that his E ability deals Magic Damage, so I like to pick this mastery.

On jungling, I think that having 15% more time of buffs well compensates Havoc's 5% additional damage.

A must have for chasers.

A must have if you are jungling.

Works wonders if the opposing team has hard CC, but feel free to replace this one with a preference of yours, such as:


Remember that teleport works quite good with Wriggle's Lantern active.
I rarely find myself using this one with Lee Sin, due to his high mobility. Still, I can think of this being used in some tower dives. I know there are people out there who take Flash with every single campion they play, so use it if you're one of those. This is also useful for a better positioning before using Dragon's Rage, to push the enemy to an ally turret.


Do not take (seriously):

Lee Sin's passive is a fine tool to keep your abilities spammable, as well as to improve his harassment capabilities. Is works fine in conjunction with Iron Will when your only option is to tower hug; remember to hit those minions twice!



Sonic Wave: This is a soft nuke that is very spammable. Making it a skill shot is actually an advantage, as you can aim for someone on the brushes or invisible.
It will:
-Reveal enemies hidden in brushes
-Reveal invisible enemies, such as Teemo, Twitch or Evelynn.
-Hit for damage a visible Teemo's Mushroom.
-Hit for damage a visible Sight Ward ward.
It won't:
-Reveal an invisible Teemo's Mushroom.
-Reveal an invisible Sight Ward ward.

Resonating strike: This is the follow of Sonic Wave. It has a very long range, quite suitable for tower dive or pass through walls. You can use it also on jungle creeps when running away from the enemy team.



Safeguard: A very nice dash. Tipically Lee Sin's fleeing dash. The shield isn't that good, but still viable to minimize some nukes or Damage-Over-Time spells. Don't forget to shield your allies too when they are ignited or so.
TIP: You can use this ability on yourself (obviously there will be no dash). You can point and click the mouse on your character or simply click Alt+W to be faster.
It will:
-Dash to Teemo's Mushrooms.
-Dash to Sight Ward Wards.
-Pass through walls.
It won't:
-Dash to structures (turrets, inhibitors, nexus)

Iron Will: A survivability tool. Great for jungling or keeping healthy at the lanes. Even from a distance, you can activate this just to shoot a Sonic Wave and get back a few hp.



Tempest: This is the follow-up to Resonating Strike when you are making your GTFI-GTFO combo (see Laning/Jungling section). It is a small AoE nuke that may also help when taking minion waves. An effect that should not be despized is the fact that it reveals some invisible things.
It will:
-Reveal invisible Teemo's Mushrooms, but won't damage them.
-Reveal invisible enemies, such as Teemo, Twitch or Evelynn.
It won't:
-Reveal invisible Sight Ward wards.

Cripple: This is a very nice ability. It makes chasing easier, it can slow multiple enemies in team fights, it can slow minions from shredding that dying turret, it helps you keeping you hp up when jungling. The applications are endless.

Here's a video I made showing some of the possibilities of these last abilities: Play Video


This ultimate is a powerful nuke.
If I'm fighting 1vs1, I will normally use this as a finishing blow, as I don't want to get my opponent away from me when I'm a melee fighter. The exception is when I can place behind my opponent to push him against my turret or against his escaping route.
When in a team fight, I will try to disable the most of enemies with this as soon as possible. Properly used, this ultimate resembles Sona's ultimate, Crescendo, with a bunch of damage to the knockbacked enemy.
Tip: this ability can be used to stop the ultimates of Katarina or Malzahar; remember to save him for that, as it is Lee Sin's only disable!
As it is a powerful nuke, it can also be used to avoid getting kill steals from that guy you hate in solo queue.

Next item = or or


A few words on some items:

Compensates this ninja's squishiness and has a priceless passive for those hard chasing kills.

I will take Mercury's Treads most of the times, but if the enemy team is CC-free, Boots of Swiftness provide a nice choice for better chases.

Lee Sin's damage abilities are AD-based, so one needs to stack AD.

If you feel confident enough that you will be able to keep 14-20 stacks late game, this item has a good balance between cost and benefits...Grab it!

and make perfect sense on a high-armor team.

I don't like this item on Lee Sin. Mana and ability power are useless on him; the damage output it gives is quite low; the slowing passive is better in a frozen mallet.
About his 150% damage increasing passive: it is a good thing, but not worth it. Trinity Force is a VERY expensive item. If you use that money on a AD item, you will increase both your DPS and abilities, which will compensate those harder hits.

Choose your best preference between these two, never forgeting that Guardian Angel is more than only a revival tool; it has nice Armor and Magic Resistance (MR) stats. Remember that one may suit best a particular game than the other.

This one can make the difference between a good and a fantastic player, as this is a game of small edges.

Lee Sin's is a good laner:
-He can harass quite safely
-Two of his abilities can reveal enemies in brushes
-Taking the mid lane is no problem for him, has he can harass safely and regen hp for longer laning time


Farming:
To efficiently farm, you MUST be aware of Flurry . The 50% Increased Attack Speed (IAS) increases de DPS and the Energy return keeps you abilities spammable to the point of never losing those 50% IAS.
-Hit-Hit- -Hit-Hit- -Hit-Hit- -Hit-Hit- -Hit-Hit- ...


Harassment:
Combo #1 (basic):
This combo is very safe. I call it the GTFI-GTFO combo (Get The F*ck In-Get The F*ck Out!) Sometimes you will get stunned/feared/snared but that will only take effect when you're back at the safe zone. That's how fast this ninja moves!

Combo #2 (extended):
This combo hits a bit harder, but takes more time in the danger zone. It would be wise to perform it with CC-free enemies.
Remember: to this extended combo, you need full energy and it would be wise to wait a bit between steps 1 and 2 of the combo.

TIP: Changing your key bindings so that you can "Smart Cast" your abilities can make these combos even faster!

Here's a video demonstrating combo #1: Play Video

Lee Sin is a good jungler, but only good. I personally use to lane with him, because I think he can get more kills in early laning and he kinda lacks ganking potential (imo great junglers would include Amumu or Fiddlesticks, who have more disabling abilities).
Still, I must recognize that Lee Sin's jungling isn't the worst, as he manages to keep his HP up, which is fundamental to perform ganks.
If you can't gank, more than half of the jungle benefits are thrown away.

Jungling route: BEGINNER MDOE
Especially in solo queue, I don't like to start at the blue or red buff because there is an increased chance that a ganking performed on me gets successful. So, this jungling route focuses on being safe at all times, particularly at the beggining.
The downside is, of course, that the enemy team would more easily steal a buff from you.

Round 1 (no pots will be needed):
1.1. Take a and 5 . Head to Wraith Camp. They will spawn at 1:40. Smite the blue one and auto-attack the others. Always keep your Safeguard and Iron Will up when your cooldown allows it.
1.2. Head to wolf camp and auto-attack them to death. Level 2 will come, so learn and start using it.
1.3. Twin golems. Smite one of them and Auto-attack/ both till they're gone.
1.4. Blue pill (teleport back to base). Buy Boots of Speed.

Round 2 (pots will now be required to keep yout HP up)
2.1. Start at blue buff. Remember to attack golem from the brush and Smite him at 470 hp to avoid steals.
2.2. Run all your half of the map, always keeping that hp up. Search for ganks or somebody needing for help.
2.3. Blue pill and buy Long Sword, two Sight WardSight Wards (VERY IMPORTANT) and some more Health Pots.

3.1. If the enemy team has a jungler of their own, place a ward at the river (baron or dragon, your choice) and keep jungling your half of the map.
3.2. If the enemy team has no jungler, WARD THE RIVER FIRST and then steal their buffs.


Here's a video of me performing this jungling route:
(it's in a custom game, with no enemies, only for route demonstrating purposes) Play Video
Things to remember while jungling:
-Keep your HP up. You are a useless as a ganker with a low HP.
-Keep checking if any member of your team needs help in a gank or in defending his turret.
- WARD THE RIVER (really, I can't tell you how much this is important). Ward the side you feel the danger is more prone to come or both, at baron and dragon. As a jungler, you are responsible for early/mid-game warding. Those wards are well worth the money, as one kill for the team will easily pay for them. Don't forget also to use your Wriggle's Lantern active!

Lee Sin is a very good AD champion, but with a lower DPS than usual.
However, he is very well balanced with a set of skills that can compensate his lack of DPS. He has two dashes, one slow, one knockback and a shield. They all synergize in a great way.

Remember please to comment and vote.
I will make my best to keep this guide updated (hoping they won't nerf the Monk!).

Hope to see you at the Summoner's Rift (I stand for the nick KABOOOMM at EU servers).

(Too Long; Didn't Read)

-Take mid if you like it
-Jungling is also fine (WARD THE MAP!!)
-Use your abilities; none of them is useless!
-Boost your AD. Don't forget those Elixir of Fortitude.