I am playing LeBlanc a lot and i settled on this build which i decided to share with you, guys. It relies completely on you not getting hit by any form of hard cc - or you die. But if there is a character that can accomplish this and still be able to jump in and do damage, its LeBlanc.

I play LeBlanc as a midding champion, so i will mostly focus on mid strategy.

Your main goals on mid lane will be to:
a) Outfarm your opponent if possible
b) Deny your opponent farm
c) Kill you opponent
In this specific order.

If you are against a ap carry that is scared near the tower, not farming, you do NOT dive him. You outfarm him.

If your opponent gets low on hp and stays close to the tower, what do you do? Yes, outfarm him.

If your opponent is stupid enough to give you the opportunity, you kill him, which will help you accomplish (a) and (b) more easilly.

However your main goals overall will be to:
a) Win mid lane
b) Help your teammates get fed (more on this topic later)

LeBlanc is made over mobility. Boots will emphasise that, and allow you to get 600hp stored in Health Potions. This should allow you to drive anyone away from the lane, unless you screw up and get cc'd.

After you go home, buy yourself a kage's lucky pick. LeBlanc sucks at fast farming and if your enemy is a pusher, you might get pushed close to your tower and not be able to get all the lasthits (Typically morgana swamp). Kage's lucky pick gives you a bit of ap and a really nice sum od gold overtime to compensate. When you can, upgrade your Boots to Sorcerer's Shoes.

This is pretty much your "small core". Now get Rabadon's Deathcap - if you get anything else, you will be lacking damage later and it will suck. After rabbadon's, get Will of the Ancients for spellvamp and then Void Staff.

This is your "large core" - it is enough to do a lot and be really usefull - even in late game. However, now it's time to get some resistances.

Abyssal Mask A very good item is, which will make you survive random AoE's a lot easier.

Zhonya's Hourglass, I do not recommend this item even though it can be a really good item too, you just need to be really careful when to use it.

Lich Bane is an awesome item, since lb has a nice autoattack range and a lot of ap from previous items.

Deathfire Grasp is a pain on lb. This champion is so easy to mess up even without that one additional spell, that i feel DFG is not worth it. It got me killed too many times trying to click everything in the correct order and dying from misusing distortion. If you feel like you can manage the micro, get it. If you aren't a hard-core LeBlanc player, stay away from it or use it in a different build.

Also, get plenty Health Potions. It's a cheap way to enable you to stay agressive.
You might also get a Doran's Ring if you feel like you need it. I do not recommend doran's spam, since you don't really need that mana and hp. Investing your money into Rabadon's Deathcap gives you more ap to work with. Plus, the hp from doran's spam will only make you feel safe, which is bad. If you get snared out of position by swain and you have a Doran's Ring, you will still die.

Rod of Ages: Bad. If you get stunned without RoA, you will die. If you get stunned with RoA, you will die. And it gives less ap than pure ap items for the same price.
Rylai's Crystal Scepter: Bad. The health reasoning is same as for RoA. Slow is useless, since you cannot stay near the enemy anyway. And if you can, you hit him with Ethereal Chains.
Mejai's Soulstealer: Bad in this build. If you get mejai's, you want kills. You want to get your stacks. That means, you will try to get all the kills you can. In this build, i focus on getting my team fed as well, not only myself. Because of this fact, mejai's is not as usefull as it would otherwise be. Because you want your team to get fed, you leave some kills to them, which results in you getting stacks only from assists. Rabadon's Deathcap should be more usefull and reliable in this scenario.

For popular demand, i will explain the idea behind my item choise:
LeBlanc needs damage, that means AP. Since i don't need mana regen or HP, i don't get Doran's Rings. Since i don't want many kills, i don't get Mejai's Soulstealer. So i need another small, cheap, 'starter' AP item. It could be either Hextech Revolver or kage's lucky pick. Why not taking the revolver? Cause the spellvamp is fairly weak in the beginning AND cause it's more expensive than the lucky pick.

I want spell penetration and as much AP as possible, as fast as possible. Kage's lucky pick gives me a fair amount of AP to start with, plus it generates gold overtime, allowing me to get Rabadon's Deathcap sooner.

This item build maximizes your damage throughout the game without forcing you to grab most of the team kills. I have tryed to play without the kage's lucky pick (i got a few doran's instead) and it was weaker. I was missing a bit of ap, my rabadon's deathcape was delayed and i was having problems with my damage output. The little blue dagger seems like a silly pick, but it is actually worth it.

Sigil of silence: It is your harrasment tool, killing tool, silencing tool. Use it every time your enemy gives you a chance to do so.
Distortion: Max this after the sigil for two reasons:

Lower cooldown on an escape spell is nice

Ethereal chains are hard to hit, plus you must get close (it's not instant like sigil)

Ethereal Chains: Use it to trigger silence from your sigils OR to get away from some angry melee dps. For both uses, level 1 of this spell is all it takes.
Mimic: A few tips on how to use mimic. Well, just one - try to mimic sigil of silence, it deals the most damage in least time. But again, you can mimic anything, just be creative.

A few combos:

Harras combo: Distortion in, Sigil of silence, Mimic sigil of silence, distortion out.

Killing / agressive combo: Distortion in, Sigil of silence, Mimic sigil of silence, Ethereal Chains, ( distortion out OR wait until Sigil of silence comes off cooldown and deal more damage).

Punishing combo (Against guys that think walking towards you is a great idea): Mimic sigil of silence, sigil of silence, maybe Ethereal Chains is the dude doesn't back off. If they get angry, you can always distortion away, since they were kind enough to walk to you. This combo does a bit more damage unless you hit the chains, then it's the same.

Camping combo: You are in a brush and the enemy nocturne is going right into it. What do you do? Sigil of silence, Mimic sigil of silence, Ethereal Chains, Distortion. If he still isn't dead, your sigil of silence will come off cooldown. If he still isn't dead, this action was a bad idea and you will probably die (unless you flash behind a wall or something). So be sure to have enough ap if you do this adrenaline camping.

Now we get to the part where you say: Why the hell Clarity?! Why not Ignite?!!

It's simple. If you stay on your lane till level 6, clarity enables you to wreck your opponent with the shear amount of sigils you can land. After that, you don't need the ignite to deal damage.

However, if you wander around the map before level 6 and without having your small core - you will lack ignite, enemies will run away with few hp and it will suck.

So stay on lane till level 6 and beat the **** out of the enemy midder. That's why you are here, not to run around the map lurking in the brushes, that will come later.

Now why Flash? LeBlanc already has 2 flashes of her own, or not? Technically - yes. But most people are not stupid and will not walk in range of your spells - that means, if you want to hit them, you will need to use Distortion to get to them. And since your ultimate is such a nice offensive tool, you will use it in the combo before distorting back from the enemy. But that leaves you with no escape spells for more than 10seconds - and that is the time the enemy will strike. Flash takes care of that weakness - if you have flash, you can get aggressive and still not die when ganked.

When using flash, take your time. If there is a jungler charging towards you, flashing right away towards your tower might not be a good idea. Run around a bit, use you eternal chains to slow him down. Flash after he gets to you - give your Distortion time to refresh from cooldown. Cause then you can "flash" again. Of course, sometimes you want to flash right away and GET THE HELL OUTTA THERE, which might be a really good idea. I am just pointing out that sometimes waiting before flash might save your life.

I've heard this thing so many times - and it can be so true, if you don't play correctly. Late-game LeBlanc has two main problems:

She gets most of the team kills, making her teammates weak.

She gets no kills at all being utterly useless.

The thing in playing a good LeBlanc is also managing your kills and letting your allies killsteal. You only need that many kills to be good, then you should try to leave other kills to your allies. You will be useful in late-game if you have: Rabadon's Deathcap, Void Staff and Will of the Ancients. You do not need anything more, especially if it would mean getting kills that your allies could otherwise get themselves. Assist your team, blast the enemy carry, so your teammates can pick up other kills. Gank other lanes, but if you can choose, let your allies get the kills. Never steal kills unless you are lacking your basic items. Your goal is to get a little fed, then help feed your teammates.

Now what the hell is this all about? It's about giving kills to your allies :)

LeBlanc needs a strong team. If your team is weak, you cannot engage and win. Now to help your team get strong you do this: Win mid. Outfarm / get a kill / zone / whatever. Just win it and get yourself an advantage. After you have an advantage over the enemy mid, go gank other lanes - and tell your allies to killsteal from you if possible. Cause if they do, you used your advantage to give advantage to your teammates as well. And that is exacly what you should be doing.

When you have your small core: Sorcerer's Shoes, kage's lucky pick, you need one kill or none. It largely depends on how the enemy midder is doing. However, you should donate your 2nd, 3rd and so on kills to your team. Does your jungler gank mid? He can steal if you already have 1 kill in this stage of the game.

Later on it's pretty darn simple. If you feel like you're not doing enough damage, get some kills. If you feel comfy, donate kills to the team. (a good way to see if you have appropriate damage is trying to burst the enemy carry with sigil of silence, Mimic sigil and Ethereal Chains. If you cannot do this, you might want a bit more ap=kills).

Pros:

Very good damage

Extreme mobility

Great ganking capabilities

Great laning power

Cons:

CC = death

Weak in direct combat until level 6 - lacks ignite.

Needs good map-awareness. If you walk into a brush, be very sure that it's empty. Watch the mini-map for missing guys. Yelling "Where was the mia?!" can warm your heart, but you will still stay dead.

Needs good gamesence. You need to know when you are overextending (and junglers will be likely to come gank), what sumonner spells the enemy has, what he's capable of, what you are capable of. Don't go past half the map if you don't have flash up. Etc.

Mordekaiser. Stay away from him, he is the counter to this play-style.

Teamfights work like this:

You stay back, out of range of everything.

Someone initiates, you wait till someone valuable (carry, ulting fiddel) is in range of your distortion. You jump to him, do your combo, jump out. You do NOT stay.

When most people are dead, you can go in and help clean up. Should be easy, just avoid being hit too hard. Remember - just jump in and out unless the AoE guys and high-damage guys are dead.

In order for this to work, you need a strong team to initiate 4v5. So help feed them, because you cannot jump into 5 people and start killing - at least one of them is likely to be fast enough to stun / snare you and you'll die.

Lasthit using your autoattack. LeBlanc has a really nice autoattack animation, it is easy to do (when you get the hang of it). If you cannot do this, learn it, it's worth it.

It is generally bad to use your spells for farming, unless you are absulutely certain that you are the only person on lane and you need to kill creeps fast. Otherwise you might find out that you are under attack and are missing the spells you just used for farming.

If your creeps are getting pushed, try doing you harrasment combo ( Distortion towards the enemy, sigil of silence, Mimic sigil) in a way that the first distortion will hit the minions. That way you are harrasing AND pushing the creeps back at the same time.

Mid to late game, you can farm clumps of minions using Distortion & Mimic distortion. Always hesitate to use Mimic distortion for farming if your Mimic is level 1 - it has a long cooldown and you might need it later.

In my opinion, mid utilizes most of your advantages.

You have a short way to your tower in case you need to retreat. You are hard to zone for the same reason.

You are able to effectively gank both lanes from mid, it's a short way.

It's a 1v1, for which this LeBlanc is really strong.

Now what about top solo?

If you go top solo, you need to ward. LeBlanc is prone to ganks and flash will only help to a certain point - if you get too far away from the tower, you can get caught.

There are brushes. You can use this to your advantage, but if a renekton occupies your brush, there is not much you can do about it. You cannot hit him, and he can wait for you to make a mistake. Or he will try to zone you once your minions push past that brush. Solvable by a ward - which costs gold. I feel like top lane gives too many opportunities for the enemy to hide / set up a gank - it's not as safe as mid.

What about a duo-lane?
LeBlanc on duo-lane can work briliantly. By any means try to occupy the brush. Then move just a little bit out of it, hit some enemy with sigil of silence and quickly move back into the brush to get stealthed again. The problem is with Crowd Control - you really want to stay clear of that, and with two enemies on bot lane is gets increasingly difficult. On bot lane, you also want to ward, since you will most probably be zoning your enemies (from your position in the brush) and they will call their jungle to help.

This LeBlanc has good damage throughout all stages of the game, can dominate lane with the clarity, can help teammates to get fed. If she's caught by cc, she dies. Don't get caught.

If you feel that i forgot something essential, tell me in the discussion. Also, if there is a similar build, link me in the discussion, i will put the link to that build in here.

I hate to do this, because i think it's a waste of space and time, but since i'm getting so many -1's, here is a screenshot that this really works.