Lee Sin is a very hard champion not only for you to master, but if you just wanna have fun with him. Only few people truly know how to handl his force and atlist in some turms i will give you my advises to be more effective with him

Pros

- Good Laner + haraser
- Good Jungler
- Good ganger
- Bruiser, pro burst

Cons

- You have to be really go to do all of the above
- In a competitive team his role is still a bit of fluid

I m personaly using armor p at quintences, armor at seal and magic resist at blues. But thats just cause this build allows me, compined with the 6 defencive talents at defence, having 52 magic resist and 34 armor at 1 lvl.
Even thgough this build feets more my shoes, lee sin has an exelent passive that you have to take advantage of it. If you think you can really play carefull with him and take the spots he need in fights and in harasment, use attack speed and you will see the diference

I m using doran blade or shild first item, cause his energy allow me to put some deffencive runes. So, you can start with a tremendus amount of defence and mr for the lvl 1 and some really good damage with dorans blade.
The 3 first items of him are the most important. Its really crucal to take Mercuries tread - cause you will take some really heavy fire and you will often have to chase- trinity forge - cause he gives you everything you want + the amazing for you ability of sheen- and banshes veil. With those 2 items you can really do a lot of kills and handle a fight situation.

Your passive is really exellent. You can notice that he can do a lot of tricks with his skills, makes him worth to master. Just remember 1 think, DO NOT SPAM HIS SKILLS. Is the diference big? IT IS HUGE. If you take advantage of his passive, you have 3 * 2 amazing abilities to use to handl any situation: Burst damage - chase - assasinate, Shield (energy back) - lifesteal - spell vamp, Aoe damage - GREAT AOE SLOW of movement and attack speed.

Just remember guys, this champ needs a lot of skill. In my opinion he is far more hard than everyone else in this game, but thing are not that taugh. Just listen my advises and try to improve them. The thinking is still the same

Summoner Spells

Recommended Summoner Spells

Flash-Teleports your champion to target nearby location.
Both survival and chasing spell. You can avoid getting killed in a team fight if you positioning is poor or you can close up the distance between you and your enemies and caught them by surprise and maybe kill them or just harass them. Actually because the distance you move ain't that long i personally use it to pass through thick walls.

Ghost-Your champion ignores unit collision and moves 27% faster for 14 seconds.
I pick this spell for the same reasons. Your chasing ability is poor so by using it you can run faster, through minions and aid your team in a fight, chase down enemy champions, defend turrets or even avoid dying.

Optional Summoner Spells

Teleport-After 4 seconds, teleports your champion to target friendly minion or turret.
This summoner spell has several uses. Mobility, ganging and lane control. You can cast it on Sight Ward / Vision Ward, on Noxious Trap and on Jack In The Box if you have Teemo or Shaco in the team. When laning just recall to your base and immediatly teleport back. That way you'll give your enemy a hard time pushing. Remember when teleporting to a minion it makes it invulnerable but when teleporting in a turret it doesn't.

Cleanse-Removes all stuns, slows, taunts, fears, snares, sleeps, silences, blinds and immobilizers and reduces the duration of newer applied ones by 65% for 3 seconds.
Yes you can choose this spell if you have a hard time escaping gangs. It's the most reliable escape mechanism because it removes all CC from your champion and reduces CC on your champions for a few seconds afterwards. It's usually used by squishy champions like Caitlyn which have a hard time getting a hit because it may lead to their death.

Note:Keep in mind that it doesn't remove Warwicks Infinite Duress and Malzahars Nether Grasp

Clairvoyance-Reveals an area of the map for 6 seconds (castable anywhere).
It may seem strange but you might choose it. With this spell you can check for incoming ganks and escape even before you engage. You can reveal jungling spots in case of enemy jungler or even you may cast it in brushes in every line to save you allies from an ambush. Use it often since it has low cooldown. Finally it can provide you with the sight you need to finish off someone with your Ace in the Hole.

Exhaust-Exhausts target enemy champion, reducing movement speel by 40%, attack damage dealt by 70% and ability and item damage dealt b 35% for 3 seconds.
Pick this only if you love 1v1 or you go for offensive play style. Use it to save youself by casting in on the most dangerous enemy or you can save your allies by using it in a team fight on a hard melee carry or AP caster.

Ignite-Ignite is damage over time spell that targets a single champion, dealing 50 damage plus 25 damage per level over 5 seconds. Ignite ignores enemy Magic Resist, and reduces healing and regeneration by 50%.
Well the description says it. It's a DoT on enemy champion which can help you to successfully score a kill when used with a skill combo. Also its effect of reducing healing and regeneration by 50% is helpful when chasing or fighting team fights. Common example is the use of it on Dr. Mundo to minimize his Sadism healing effectiveness.

Note:If you run Exhaust and Ignite you go for aggressive gaming only and no escape tactics. Keep that in mind before choosing your spells.