Hey guys. This is my first Champion Guide so far. I've been playing her for a long time. Lux is also my favorite champion. She is a cheap champion with powerfull abilities. Her ultimate is awesome. It does lots of damage and has a HUGE range. One character that has come out of the fray of new champions is Lux, a variety of assortments to the team that can carry a team, and make or break a team fight.

Pros:

Very fun to play
Long range Abilities
Can double stun and support her team
Can lane in all lanes easily
Her ultimate can have 24 sec cooldown
Powerful abilities

Cons:
Difficult to play
Difficult to Escape
Low Health and Armor

Runes:

9 x Greater Mark of Insight - +0.95 Magic Penetration
9 x Greater Seal of Clarity - +0.065 mana regen / 5 sec. per level (1.17 at champion level 18)
9 x Greater Glyph of Clarity - +0.055 mana regen / 5 sec. per level (0.99 at champion level 18)
3 x Greater Quintessence of Ptency - + 4.95 Ability Power.

Greater Mark of Insight. These are very usefull in early game. It will be easier to cut through enemies base Magic Resistance.
Greater Seal of Clarity. These are usefull because without Mana, Lux is nothing.
Greater Glyph of Clarity. These are usefull because without Mana, Lux is nothing.
Greater Quintessence of Potency. With these runes, you'll have about 30 Ability Power at the beginning of the Game. This will allow you to hit harder and get more kills in early Game.

Items:

You want to start with a Doran's Ring. It gives nice stats for early Game. And with your Runes and Masteries, you will have about 35 Ability Power at the beginning of the Game.

I'd suggest buying Kage's Lucky Pick as soon as you have 765 gold. It makes it alot easier to farm gold.

If you think your gonna make alot of kills. Get your Mejai's Soulstealer first. If not, get Boots of Speed and then you will have to go for Mejai's Soulstealer.

I'd suggest to buy your next item: Sorcerers Shoes. You will have more Movement Speed and Magic Penetration.

If you're already getting kills, and if you have enough gold, buy a Blasting wand or Needlessly Large Rod, and quickly get your Rabadon's Deathcap.

Next: If you're playing against a tank, this item will be VERY usefull. get your Deathfire Grasp. It gives 60 Ability Power. 15% CDR, and her powerfull Active: Deals Magic Damage equal to 30% of the Target's HP + 3.5% for every 100 Ability Power you have. When you have 700 Ability Power. You deal Magic Damage equal to 55% of his current Health. <<< That's amazing.

Now get your Void Staff. It gives some Ability Power and 40% Magic Penetration.

Finally get your last item: Lich Bane. With this item you'll hit over 1000 Magic Damage with your Ultimate and get some real kills. And you'r Auto attack deals over 500 Magic Damage.

Lux is at her best with her Team Mates around.
She can shield them with her W Ability, Double Stun her Enemies and slow them.
She's very squishy, so NEVER Jungle when your Team Mates aren't close to you. And keep out or range of enemies. Just spam your Abilities and stay out of their range. Attack when your Abilities are ready

If you're going mid, don't lock down unless you have a clear shot and some time to get some hits on them. Lucent Singularity, however, you should spam every time it's up. If you are going mid, save your clarity until you get your ulti. If you've been harassing with Light Binding and Lucent Singularity, their health should already be low, and you can easily get a kill. If you're laneing, clarity should be used at 3.
Lucent Singularity is an AMAZING scouting tool. Throw it into bushes or anywhere within your range you can't see and it will reveal a small area. It's great for spotting enemy ganks and turning it back on them.
Finales Funkeln doesn't hit hard at early game, but its so usefull. When you are damaging your Enemy, and they are running away with low Health, use your Ultimate when you think he is recalling at the turret. BOOM, he didn't saw that coming, and you got a kill.

I love to play with Lux, and this is my Personal Build. I'm always using it.
I will continue to Update this Guide. I would love some Comments and rates from all of you ;)
Enjoy the Guide and have fun playing!

~Dupix