Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Lux is a pretty good champion, but many people think she's onl good fed. Not with this build. You will only need a few stacks with your Mejai's and your ready to go. If you hit 20 stacks, get blue buff. With this and Mejai's, your laser will be ready approximatley every 30 seconds. If you aren't killing alot, instead of wasting money on the soulstealer, buy a Rod of Ages, or a Rylai's Crystal Scepter, depending on your needs. These items are robanly the biggest decision in the build.