Intro
LeBlanc is an assassin type mage with amazing burst capability. She is one of my favorite champions as she requires tactical planning and an extremely fast execution of skills to be deadly.

Version History
1.0 - 5/26/11 Guide Published

Story
Every city has its dark side, even one whose reputation is already of a questionable hue. Noxus - though its name is already invoked with a mixture of reverence and revulsion - is no exception to this simple truth. Deep within the winding dungeons that honeycomb the earth beneath its dark, meandering streets lies the real underbelly of this sprawling metropolis, a haven for all manner of malevolence. Amongst the cults, covens, and secret societies that call this labyrinth their home, LeBlanc, the Deceiver, presides over the Black Rose, a remnant from a lost, yet similarly unscrupulous time in Noxian history. Ruthless and seemingly ageless, LeBlanc and her ilk were a mainstay in Noxian political affairs during the era before the militarization of the Noxian government. In those days, this guild of powerful magicians met in secret to further their hidden agenda, and to hone a craft more subtle than that preferred by those currently in power.

While their exact motives have always remained mysterious, it was widely believed that the Black Rose was the true power behind the throne while the aristocracy still reigned in Noxus. When raw martial prowess became the ultimate determination of whose will held sway in the Empire, the Black Rose seemed to vanish overnight. Many believed that perhaps their time had simply passed, and that its members had put aside their quests for social and political dominance. When LeBlanc reemerged at the gates of the Institute of War, however, it became clear that these masters of shadow and flame had simply been bidding their time, waiting for a new global authority to emerge: the League of Legends.

''The world is very different for those who cannot see beyond what is placed before their very eyes.'' -LeBlanc, the Deceiver

Runes
Greater Mark of Insight x9
Magic penetration Marks. Makes LeBlanc's spells hit even that much harder.

Greater Seal of Clarity x9
Mp5/lvl Seals. Mana regeneration, not much to say here.

Greater Glyph of Force x9
AP/lvl Glyphs. You could also use flat AP glyphs, but I find that LeBlanc isn't that burst happy until level 6 when your get mimic. By then the AP/lvl glyphs are almost equal to the flat AP. Little bit more AP in endgame is also quite helpful for LeBlanc.

Greater Quintessence of Force x3
AP/lvl Quintessences. Same thing here as the glyphs. You could use flat AP, but I find AP/lvl to be more useful.

Masteries - 9/0/21 Build
Offense
Pickup AP/lvl, CDR, and 15% magic penetration.

Defense
Nothing here.

Utility
So much good stuff in here for mage types. Regen/Mp5, Experience to get level 6 faster, Longer blue/baron buff, Move-speed, CDR, and summoner spell CDR.

Items
Doran's Ring

Even after Doran cost increase I still find this to be the best starting item for LeBlanc. HP for more survivability, AP to help (Q) Sigil of Silence harassment, and finally Mp5 to let you (Q) Sigil of Silence harass more.

Sorcerer's Shoes

You should be able to farm in lane until you can purchase these on your first trip back. These amazing boots will make your abilities hit harder. These boots combined with the magic penetration marks will get you close to true damage against squishy champions such as Ashe, granted they don't have MR runes or items yet.

Health Potion

During the first trip back I try to pickup as many health potions as I can (up to 4). These allow you to be a tad bit more aggressive and keep you in the battle longer. Also quite useful to have if the enemy team has a Karthus. I generally refresh my stock of potions anytime I return to base.

Haunting Guise

This is the next item this build aims for. This item will increase your damage output and give you more survivability. Sometimes during a low kill game you will be unable to get this item on your next trip back. If that is the case, pickup Amplifying Tome first and then Ruby Crystal. Don't forget to pickup Health Potion as needed.

Rabadon's Deathcap

Your main source of AP. This item is just plain fantastic for AP champions. Once again, if you need to return to base before you can buy this item outright or just need a bit more AP to get your kills get either Blasting Wand or Needlessly Large Rod first depending on how much gold you have or how close your targets are close to dieing after your skill combos. Blasting Wand if close / don't have the gold or Needlessly Large Rod if not close / have the gold.

Fiendish Codex

AP/Mp5/CDR. Allows you to hit harder, maintain mana pool, and use your skills more often. Also a building block for your next source of damage output.

Deathfire Grasp

I like to call this item the "nuke stick." AP/Mp5/CDR and a "nuke" active. AP improves your skills damage, maintains your mana pool with Mp5, and allows you to use your skills more often. Put this item on an easy to hit number such as 1 or 2. You will be using it first during your skill combinations for maximum output.

Banshee's Veil

Anti-CC/Survivability item. If the enemy team isn't already trying to focus you because of your burst damage, they will once you get Deathfire Grasp, as it will be quite obvious where the damage is coming from.

Skill Sequence
Leveling
Skill selection is at top, however, here is a simple display of leveling priority.

Skill advancement priority:
>Sigil of Silence> >

Basically level (R) Mimic when possible. Followed by (Q) Sigil of Silence, (W) Distortion, and (E) Ethereal Chains.

Usage
Skill usage really depends on what situation you are in. Take a look at Riot's spotlight on LeBlanc if you don't know what I mean. A great LeBlanc player will know what spell they need to Mimic at any given time. However, I will list the "nuke" combinations.

LeBlanc's main nuke is much like Akali's. Procing the seal is the key. I try to save (W) Distortion as a Flash or (R) Mimic'd (Q) Sigil of Silence seal breaker.

Therefore, if target is in range:
(1) Deathfire Grasp
(Q)Sigil of Silence Sigil of Silence
(R) Mimic
*If you don't need to escape / need the AoE damage*
(W) Distortion
----OR----
*If need possible escape / don't need AoE damage to proc seal*
(E) Ethereal Chains
(F) Ignite

If you can use a wall / surprise attack / not in range:
The key to this combo is getting all skills off before 3 seconds so you can use (W) Distortion to return to safety.
(W) Distortion
(1) Deathfire Grasp
(Q)Sigil of Silence Sigil of Silence
(R) Mimic
(E) Ethereal Chains
(F) Ignite

NOTE:
Like I said before, these are the basic "nuke" combinations. A good LeBlanc will know when to nuke and when not to nuke, thus saving (R) Mimic for the right time.

Summoner Spells
This Build
Ghost
I find ghost to be a lot more useful in terms of utility than Flash. You can use it to return to lane faster, catch up to a team fight, escape an incoming gank, etc.. A talented Ghost will allow you to catch up to a champion using Flash alone. I also believe it forces you to think in a more tactical manner.
Ignite
Reduces healing and really gives you that extra damage you need. I've gotten many first blood due to having this summoner spell and can't see living without it anytime soon.

Other Possible Spells
Flash
A get out of jail free card, granted you're not currently under CC. I feel that (W) Distortion gives LeBlanc all the escape she needs. Especially combined with (R) Mimic. However, this can be used instead of Ghost.

Cleanse
If playing agaisnt a CC heavy team this summoner spell is amazing. Cleanse + (W) Distortion + (R) Mimic = GET ME OUT OF HERE, NOWWWW!!!

The others
Not too useful for LeBlanc. Use only if you really really really really want to...

Farming
LeBlanc has an amazing attack animation for a mage. It is very important to be extremely skillful at last hitting. Focus more on getting CS than champion kills (at least until you get (R) Mimic), as you will benefit greatly from the gold.

Champion Farming
Yes, I did say champion farming. There will be games where you farm the enemy team. You will get a feel for how much damage you can burst on enemy champions as the game goes on. Check for champions with low MR and punish them with a free trip back to their base whenever they over extend themselves.

Summary
LeBlanc is a very fun and somewhat intense champion to play. I've played many games with her and still consider myself to be far from mastery of her. Don't be discouraged if you can't get the quick combinations down right away. Just keep working on it and trust me, you will enjoy the fruits of your labor. I thank you for the time you have taken to read this guide and I hope you have great success with it.

P.S.
Please try the guide before you vote. Also when you do vote please make sure to include some constructive criticism. I cannot improve the guide and my play without constructive criticism. Thank you, for taking your time to comment/vote.