This is a guide to teach you how to play Lux, the lady of luminosity.

First, always try to get mid, as with the teleport spell, the tower will be pretty much safe.
However, if you are up players like Vlad, give mid to someone else.

From level 1 to level 5, harass as much as possible with E. But try to anticipate where the ennemy will walk as you dont want to waste your mana.
As soon as you are out of mana, use Clarity.

If you manage to get the ennemy low health, try to save up enough mana for when you get level 6 so that you can snare and lazer him. I have killed many that way.

From lvl 10 to lvl 18, use your lazer as much as possible as it is on short cooldown. For example, if you about to b, first shoot your lazer and then back, considering that after b, buying your items and being back at your turret, your cd is already down to 10 sec or so.

Team fights : Shoot your lazer at the beginning and at the end to get the fleeing low-life ennemies.
Also, Lux can actually initiate fights. You have to go up front and snare the coming ennemies that way, your allies will jump on them right away.