Pros
Very good burst people will get annoyed when you just turn around and kill them with a 1-2 combo
Very nice at escaping ganks
Has a CC that can kite anything
Very strong early-mid game

Cons
Even though her early-mid is strong she is still very squishy in those lvls
Late game can be a nightmare
between CD not much to do
Slow movement (391 with a proper build)

Ignite Good for early kills, trust me you will need them
Ghost Chase and exstra escape? , this makes a Full CD LeBlanc Impossible to catch
Flash You may consider going Flash instead of Ghost just to get the third teleport and it is a Surprise maker
Cleanse if they have alot of stun you want this to escape

To Start off you want a Dorans Ring or a Amplifying Tome for the Haunting Guise. when you get to your lane (mid or due imo Leblanc can do both) play passive until lvl 3-4 and get as many last hits as possible. at lvl 3-4 you (and your lane partner)should be able to kill the enemy champion that your laning against if you stil need that little exstra burst go grab a Elixir of Brilliance. when you hit lvl 6 Leblanc mid game starts and you should have shoes and maybe even a Haunting Guise.

When you hit 6 and get a Haunting Guise you should start looking for ganks in the other lanes(imo Leblanc is aq superb ganker). if you see a gankable lane then by all means go and grab that kill you will need it for your Rabadon's Deathcap. after the gank retreat to your lane, and maybe get a kill by surprise. Remember to keep your Elixir of Brilliance going for aslong as you can afford. At lvl 11-14 you should have your Rabadon's Deathcap and maybe even started building your Rylai's Crystal Scepter but when you hit the lvl 15-16 your late game begins...(ohhh horror)

Late game begins with you finishing your Rylai's. Late game imo is the hardest part a Leblanc to master, you really need to cordinate with your teammates in teamfights because until you get your Banshee's veil you will be picked of easily if you get into the teamfight at a wrong position. but if your Team is overall wining everything i dont think you should grab Banshee's go for a Zhonya's Hourglass instead, for the exstra burst and if all ****s up you get the nice passive (trust me ive made alot of good escapes while using Zhonya's Active.

-If Mimics next spell is SoS try to get in range so you can cast the mimiced SoS first and then the ordinary SoS. that is a great killing tool
- When your retreating go in forest and kite the enemy following through with Ethereal Chains and try to kill them or simply just use Distortion and mimiced Distortion to GTFO
- Katarina is a very fun lane partner to have, though that lane misses some Tankyness

Hello this i Roknaroz i just wanna remind you that this is my first build and my english isen't the best. So if you would be kind to leave some positive Feedback i'll maybe make another build soon!

Gl & HF with my build
-Roknaroz