Hello my name is Rogar and I've been playing Lee Sin for quite a while now. I started playing league of legends in the beginning of season 3. I am just an average player and I've been mid plat for the past 2 seasons now. I'd like to share my Lee Sin knowledge because as I have experienced myself not all high elo guides suits low-mid elo players.

Ps. I'd love to get some comments on what I can do better, both on how to play lee and also how to make a good guide for you guys as its my first guide ever.

In my experience Lee Sin is the most versitile champion in league of legends. You can choose many different playstyle and builds to help you win games.

Lee Sin is the strongest early game champion in my opinion. Maybe not always the best in 1v1 over a silly scuttlecrab, but the best when it comes to fighting, ganking and counter ganking. Lee sin got incredible mobility thanks to his kit. He also got a good engage, disengage, peel, gapclose and the ability to assassinate certain champions.

Lee can be played to take out enemy backline as much as being used to peel for your carry. The biggest problems with Lee sin players in lower elo is the egotistical behavior when it comes to fighting, a lot of players have the idea that they are the best. Lee Sin is a complex champion, you need to know the damage output, when to engage, mechanics and playstyle. Most players always wants to be the flashy insec god, instead of playing as a team, causing them to take stupid decisions ending in getting yourself killed (which can lead to losing objectives) or getting your team killed. Lee needs a lot of practice and with practice you realise when and who to engage on.

When it comes to different Lee Sin builds it depends on two things;
What does your team need and what champions do the enemy team have?

Early:

Lee sin struggles a bit when it comes to clearing camps, this is why Tiamat is extremely good on him early, even if you dont use it to your full build, it helps him clearing camps much faster giving him more gold and more time to focus on objectives and ganking.

Lee also works well with both Skirmisher's Sabre and Stalker's Blade depends and what you prefer.

After you have finished your jungler item and tiamat, I'd get myself some boots and then go for a Black Cleaver. This is what I see as core items for lee sin.

Mid game:

I'd focus more on items to give you more survivability (unless you are going full AD). Items I prefer on Lee after I've built Black Cleaver is Sterak's Gage and Dead Man's Plate as it gives you more HP and armor, but also damage.

Late game:

Late game is usually hard for Lee as he is outscaled by most other jungle champs.
What I usually build late depends on how the game is going and what I feel is best for the situation. If you need magic resist I'd go for Adaptive Helm or Maw of Malmortius depending if your team needs more AD or tankiness.
If you need more armor I'd most likely go for a Guardian Angel as it is a really safe pick and can work really good and more safe for you if you need to be the one to engage fights.

Pros
-Insanely strong early game if played correctly
-Versitile champion
-Good mobility
-Nice damage output
-Very good snowball potential
-Good dragon and baron steal potential

Cons
-Not so strong late game
-Very hard to master properly
-Need an open mind on what to build
-Difficult mechanics

Thank you for reading my guide.
As I meantioned earlier, this is my first guide ever and I appreciate any form of constructive feedback. I am just an average Lee Sin player and not even close to being good, but this is how I've experienced Lee Sin and what lower elo players might do wrong. Lee Sin is my favorite champion and I just wanted to share my thoughts on him to you guys!

Thank you again.