This is my first guide. I'm not writing a long introduction for a few reasons:
1. I'm writing this at work.
2. If you don't know who LeBlanc is, what her skills are, or any other basic information about her then a guide will not help your game.
3. I'm lazy.

Mark
Okay so Obviously you take all MP Marks. Its just the best bang for your buck. However from here it gets controversial. I have played around a lot with the runes and let me explain my conclusion:

First off I believe doing well at the start of the game is incredibly important. The sooner you get your items and the more powerful you become early game, the easier it is to dominate. I suppose everyone can agree with this argument?

Glyphs:
Doing simple math, you can figure out that flat runes, in general, have more of an impact than per level runes. Lets compare flat AP with AP/level:

With AP/level, you get 3.06 AP at level 18. Having 9 runes, you get 27.54 AP at level 18. Normally, with just items, you have at least 200 AP at level 18 (being conservative). If you don't, then you suck at the game.
If you take (27.54/200) * 100 = 13.77%. Your runes are only 13.77% of your total AP at Level 18.
(remember, having more than 200 AP makes this percentage go down! So it can only get worse)

Flat AP Glyphs provide 0.99 AP each. That's 8.91 AP with 9. At level 1, the most AP you can get from an item at start is 20 AP, Amplifying Tome.
If you take (8.91/20) *100 = 44.55%. That is a HUGE impact. (Throw in flat AP Quints and you're rocking 23.76 AP at level 1 JUST FROM RUNES)

If you do some simple algebra, you can figure out that to reach 13.77% of your total AP with flat runes, you need 64.7 AP from items. By then you have gotten a couple kills from the runes.

Seals:
After playing around with different combinations, I find that about 4 mana/5 Seals combined with the mana/5 mastery fulfills my needs. I try to boost up my AP with the remaining slots, even though flat AP is not a Primary rune.

Quints:
I've been going back and forth between MP and AP quints... but I think AP is a better addition to both the early game and overall balance. Most champs start with very little MR and people are resilient to build defensive items (except tanks). Usually your Sorcerer's Boots do fine until late game, and the extra AP is incredible at the start of the game.

Typical AP Damage mastery pages. I have experimented with putting half into Offense and half into Utility, in order to reach both CDR masteries... however it does not help as much as the damage boosts in the Offense branch. You can always get more CDR through items. Damage % boost is hard to replace.

Why no Doran's Ring? Because it doesn't lead anywhere. Yes its the most bang for your buck, 15AP, 100HP, mana regen. But you just end up selling it eventually. More importantly, it slows your build down. Any good player can survive without the 100HP. You just need to be aware of the minimap, know when to attack, and be careful not to take minion aggro. Leblanc has possibly the biggest burst in the game. And combined with Distortion, there should be no reason you are getting harassed. That extra 5 AP from the Amplifying Tome is again a nice increase in damage and having this item early lets you build your Fiendish Codex early, which gives you AP, CDR, and mana/5 which is basically EVERYTHING you need. Its the most handy item for LeBlanc imo.

Depending on how the game goes, I try to get Codex before basic boots. Usually if I get first blood I get the Codex. Otherwise I will get basic boots.

NOTE: If you are laning mid against Anivia, Morgana, definitely Brand or any champion who has a skill shot you must dodge to survive, buy BOOTS first. It will save your life.

Mandatory Items:
Sorcerer's Shoes - The ONLY other option I can see is Ionian Boots of Lucidity but you're a nuker, you need MP.
Morello's Evil Tome - I think this item is severely underplayed in LoL. The CDR This item provides combined with the Mana/5 and 75 AP is irreplaceable. Your ult already has a very low CD. After this item, you can drop it to somewhere around 19 seconds! Imagine being able to blast off your Q+R nuke combo every 19 seconds! Not to mention the Sigil of Silence you can toss every 4.8 seconds.
Rabadon's Deathcap - 140 AP + 30% AP. Nuff Said.

To be honest, this is all you should need to win the game. Or at least kill your enemies so much that they are waiting to surrender ASAP. However you can continue to a variety of items:

Rylai's Crystal Scepter - I usually get this item because it provides a nice amount of health since their team should be focusing you hard by now. It also gives you AP and the passive comes in handy for chasing. You can get Rod of Ages as a health alternative.
Abyssal Mask is a great item if their team has some AP carry that tries to focus you down. It also lowers ALL of their MR which really helps punch them harder. However, if their team is building MR, you will want Void Staff
Zhonya's Hourglass is wonderful if they have a lot of AD that tend to focus you. Just burst their ***, run a little bit to recover from your cooldowns and until you're below 50% HP, then just as they think the kill is theirs, activate Zhonya's. If you planned this all correctly, you should exit Zhonya's stasis and melt their face with your burst.


REMEMBER: Edit your build based on the game. You are allowed to swap items around a little bit. If I end up going back to base with enough gold for a Blasting Wand before a Needlessly Large Rod then I usually get it. Don't want to fall too far behind in items or have to make an extra trip to base.

Why did I max Ethereal Chains before Distortion?


1. I mainly use Distortion for utility purposes and sometimes to trigger Sigil of silence. It gets you places quick. It adds to your range. It hops walls. It is tricky.
2. Each rank, Distortion costs more mana, which can be draining at lower levels. The damage boost isn't quite worth it. Perhaps the CDR but I don't find that to be a problem.
3. Once again, simple math comes to the rescue. Ethereal Chains does more damage than Distortion if you get the second trigger.
4. Don't forget that Ethereal Chains slows AND snares your target. I understand the required shackled duration required to trigger the snare increases (1/1.3/1.6/1.9/2.2) but that isn't really a con. That's actually more time that they are slowed and attempting to run away. Longer disable = advantage.



Why did I max Sigil of Silence ASAP? Because it is your bread and butter attack. Lowest cool down, high damage, and once you get your ult, Q provides the most damage output for it. Which brings me to the next section...

Bread and Butter cripple/kill Combo:
Q + R.
The End.

Oh and Harassment: W -> Q -> (W)
Extend your range by using Distortion to approach and retreat your enemy. I will use (W) to represent the second activation of Distortion. Just make sure you get your Sigil of Silence off in time. Great for keeping the enemy off the minions in the mid lane.

I suppose you can combine those together and throw in Ethereal Chains to make more combos, such as:

W-Q-R-(W) <-- My Favorite. Distortion is used for an increase of range, not damage. If you focus a weak squishy or just somebody who's taken some damage already, its an instant kill. During a team fight, this could be all you need to give your team the upper hand.
W-E-Q-R
E-Q-R-W
Q-R-E-W-(W)-Q <-- Long combo. It provides enough time for you to use Q twice. Good for tanks.
W-Q-R-E-(W) <-- If you are a good player, you should be able to get this done within the 3 seconds that Distortion allows you. And nothing feels better than killing somebody with the triggered snare on Ethereal Chains while you're walking away.
Now that you think you've mastered LeBlanc, let me give you a few slaps in the face followed by some pointers:

Don't just go into a fight blindly thinking your Q+R will win you the game. Think about who you're facing, how much HP they have, how much MR they have, what skills they have, where you are on the map, etc. This all matters.

With melee or short range champs, sometimes you need to harass with just Q. Even if you meet them in the river. Keep your distance and piss them off until they try to charge you. Then try to not panic and blast off skills... stay calm. Start off with Ethereal Chains. You can't miss if they are charging straight at you, pretty simple skill shot. Then try your Q+R combo before the chains activate. If done correctly, you will deal your biggest burst, silence them and mark them again. Then silence and snare them when the Ethereal Chains activates. If for some reason they are not dead yet, you can Distortion to finish them off. And if they still don't die, Sigil of Silence should be back in another second to catch them as they run. And don't forget your Ignite.

Keep in mind that it's not JUST about the burst damage you receive from your Sigil of Silence + Mimic combo, it is also about the CC you get. Each Sigil of Silence marks the enemy with a... Sigil... and if that mark is activated in the next 3.5 seconds, the target is silenced for 2 seconds. This means that if you don't rush, your enemy can be silenced for a total of 4 seconds during your barrage. Throughout this time, I would hope you've landed Ethereal Chains so your target cannot flash/ghost away once the silence ends.

Now, remember how I said your Distortion can travel through walls? You can jump into the river, over trees, and even over the wall into their base! Yes. Nothing is more satisfying than popping in through their base wall with W, killing their squishy AD carry with your Q+R, then popping back with W again. Get creative. And yes, you CAN tower dive this way. Just be ready to take 1 hit from the tower.
NOTE: In order to successfully go through a barrier, you NEED to be right up against it. This does not work like flash.

And finally, let me cover Mimic real quick. This single ability, this extremely unique ultimate, this wonderful arsenal is what makes LeBlanc so versatile and amazing. You have the ability to replicate any one of your skills, with added damage (+40% at rank 3). You can use it to escape in many ways, my favorite is double Distortion. You can use it to disable their heavily fed Tryndamere with double Ethereal Chains. You can basically use it to do anything you want. Just get used to using it.

The key to being a great LeBlanc player, is mastering the use of Mimic. Know when to use it, know how to use it, and know how much damage it will do.

However... the key to being a great Deceiver, a LeBlanc who can dance circles around the enemy team, and just dominate the battlefield, is mastering the use of Distortion.

To be honest, I don't need any summoner spells for Leblanc. She is so well rounded that you don't need another way to escape (ghost or flash) and you don't need to heal or refill your mana. I've been playing LeBlanc for over 6 months and I have tried many spell Combinations... nothing makes a huge impact on my game.

However. Ignite is VERY useful. I mean, you ARE an assassin so its nice to have a spell to contribute to your burst. It also adds 5 AP when it is on cool down. This means that while you're 1v1 in mid, you can cast Ignite at the start of your battle to gain a little bit of AP for all of your abilities. Remember that 5 AP at the start of the game is a huge increase... go back and do some more math if you don't believe me =]

Since Clairvoyance is such a useful spell for the team to have, yet a useless spell for a single champ to have (usually), I tend to pick it up using LeBlanc. After using it a few times, I realize its a GREAT spell for LeBlanc. Since you have range, burst, and even a built in Flash ( Distortion), you can use CV to scout out bushes or areas over a barrier. Then you can use your amazing-ness to pop in and pick up a free kill. Works very well for the river bush in mid.

Exhaust and Teleport can be useful too... Kind of up to you.

COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE COMMUNICATE.

Oh and also:

WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS WARDS.

These two things WILL win you games. Imagine you know exactly where the enemy is at all times? How easy would it be to gank and just dominate the whole map if you knew this information?! Well if everyone on the team buys 1 ward, this is possible. A mere 75 gold goes a LONG way. If it picks you up 1 kill, saves your life, or gives you confidence to farm more, it pays for itself.

Hope this helps out anybody who's been playing LeBlanc but just can't seem master her. Constructive Criticism is accepted, although I will warn you... I probably won't change a thing. I've read many LeBlanc guides so I know what other builds and strategies are out there. I don't agree with most of them. I'm just showing you what works best for me. I always dominate mid, I get about 15 kills per game and rarely die more than 5 times. If you ever come across me on LoL, you will witness first hand.

Please vote this up if it helped you so more people read it and I can start to see less noob LeBlanc players out there giving us a bad rep.

Enjoy.