This is my first guide and i hope you will make positive comments and feel free to vote it up. If you really feel like this guide deserves to be voted down then please do leave a comment explaining it. This is a guide on how to play lux and how to own in teamfights.
Is a ranged support caster and should be played as such, you should not be trying to 1v1 people because after your abilities are used you are very vulnerable. I have played many gmaes as lux and tryed many different builds with her, trying many different items and I have found that this is my best combo of items. I hope you really enjoy this guide, i have put alot of time into it :D

Pros
-Fanstasic farmer
-Great Nuker
-Very good in teamfights
-Your ulti will make people Rage Quit
-Very good synergy with lich bane
-Sheild to save comrads
-Double Stun
-Good team carry

Cons
-Pretty squishy
-Able to be shut down if getting to clsoe in teamfights
-People who are able to dodge your stun can ruin your combo
-Requires alot of player skill because of skill shots

As lux you need to wear down the enemies HP with your . then when you think that they are low enough and when you reach level 6 you should use this combo to get a kill
, Auto attack proc, , Auto attack proc, Finales Funkeln only do The Finales Funkeln if you think you can kill him
But this is your attacking order for max damage.
When you get your your auto attack proc will do around 750 damage, because of your normal damage(100), (190), and the (500+) so around (800 dmamage) with 500 AP.
In a teamfight you need to focus one person ussally someone like Kat, Yi, Xin, Heim, All the swqishy charaters in the game and then your teamw ill destroy them. in teamfights spam your and , and when u feel like you can get a kill or your team if loseing the fight, aim a Finales Funkeln at as many ememies as you can. Basicly in teamfights you need to stay behind you tanks and avoid getting focused, when you get your chance get in and spam them.

As lux u cannot take out a tank such as Garen at full hp. at full hp u will not be able too hurt him enough to even make him worried. Another example would be Olaf as he has more MR and some hp.

People to target should be low on hp and have a very low hp pool to begin with, so a katrina with 3/4 hp would be a fairly good target as if u hit with your skill shot she is basicly done. as she is running away hit her with your ulti only if u think she will die.

You should always try to get mid, but if someone on your team insists on taking it let them have it becasue you are very good at laning anywhere. When taking mid spam your , sparingly as you do not have mana regen, but you will have Clarify and you have some mana regen for your masteries. So you can spam it a little.

Your main goal by level 6 is to get your opponent to half health, Farm minions, and have enoguh mana do do your finish combo , auto , , auto , Finales Funkeln. So you can get a kill. then you can recall and get your items.

As lux you are a very squishy charater but, for defence we have Runes of vitality for an extra 175hp, Flash for escaping, and for and extra 500hp and a slow.
For spells you have stun and your so if you get ganked you need to flash away, hit them with your stun, adn through down a Lucent Singularity, so they run through it and they will be slowed. Just run towards towers when ganked. avoid over extending lanes and, going through the jungle alone, as lux u can not 1v1 people very easily especally people such as Garen or Sion.

AS LUX YOU DO NOT NEED MORE THAN 1 DEFENSIVE ITEM, YOUR DEFENSIVE ITEM IS IF YOU HAVE MORE THAN ONE DEFENSIVE ITEM YOU WILL NOT HAVE ENOUGH ABILITY POWER AND WILL NOT BE ABLE TO DO YOUR DAMAGE IN TEAMFIGHTS

Your goal is to get as much ablity power before the teamfights start. When the teamfights start u should be picking up kills with you Ulti and, getting assists from your Aoe spell and stun. Let no one get away if they are low on hp. Play smart and dont lose stacks.

Start off with and a which will help you lane for a while with clarify for mana. After u get 1115 gold you should go pick up Kage's Lucky Pick , , and . The Kage's Lucky Pick will help the gold start to flow for you. the lucky pick will turn into Deathfire Grasp at the end, the will turn into , and the will turn into .

After that you should try to get a and , I would almost recomend getting Blasting Wand first, as Mejai's adds no additional AP initally. Then you need to rush as its passive, +30% more AP is huge for you. I ussally get at level 12-15 depending on how I am doing. After that you should finish you boots and get for the extra magic pen, and the extra speed. For the mejai's to be worth buys you should try to maintain 7 stacks at least, im not saying you will have 20 stacks every game.
so to recap you should have Kage's Lucky Pick , , , by the time you are level 16. you should strive to have around 5-15 stacks.

Then after you complete those you can starts with your which really adds alot of damage in combination with your passive, The adds all of you AP into you next attack after you use a spell, even if u use a spell like Prismatic Barrier it still activates. so even after u use your dmaeg spells and that master yi still has 400 hp and feels compelled to chase you then use your barrier and atuo attack and hes dead.

I feel like you can wait for this for almost you last item because you have the runes to make you less tanky, but your next item is giving you 500 more hp and 80 AP plus a slow, the slow cans sometimes save you, and get you a kill. Although 15% isnt alot. This item is only there to make you less sqwishy.

The last item is , this is your anti tank weapon, you can take out 50% of the heath with this no matter how much health they have. It has a 60 sec cooldown so feel free to spam it as much as u want, it does a minimum of 200 damage. The Range of this is very low so u will have to get close for it. Also this is used as a first strike becuasw eit does damage based of there remaining hp, so i you use it last it won't do much. It also adds mana regen, cooldown reduction and 60 AP all thing you can use :)

I go with the typical 9/0/21 masteries, picking up magic pen in offence and picking up all theusefulness in utility. in utility i get movement speed, cooldown reduction, and more exp, and most importantly mana regen :). all which will help u t stay in mid longer and lvl up faster, the speed has actually saved me alot and goten me some kills, the cooldown reduction makes ur ulti up faster :D. In offence u pick up a little ability power, 3% cd reducion and 15% magic pen with you runes this should go nicely.

For runes i pick up
x9 = 8.5 magic pen
Greater Seal of Vitality x9 = 9.72 hp/lvl ( 175hp at 18 )
x9 = 1.52 AP/lvl ( 27.5AP at 18 )
x3 = 15 AP

Your starting AP is around 37 which is alot. you should be able to dominate early game with this essecally against a sqwishy champion. I take magic pen marks for early game damage, seals of vitality because it make lux less sqwishy, and glyphs of force for the extra AP that is scaling well. The Quintessance give you a free 15 AP pretty standard.

Farming is very simple
into the minions and then auto attack them activating your passive, this should kill the mage minions for sure. late game you can basicly throw a into a wave of minions and kill them all without auto attacking.