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 great support or rescue champion with her light binding, prismatic barrier and lucent singularity. She can also deal great damage if you have an illumination flare on the enemy. thats why you need lich bane. When you cast a spell your next spell will illuminate and do the bonus damage from lich bane. That is the way to take the enemys hp down fast. I used that build from the beginning a my best score wa 16-1-24. Lux is greato get assists with too so try to hit them before they die atleast.
Rod of ages is good hp, mana and AP so its good to get fast.
Zhonya's ring is great AP and can get your lich bane attack to damage really much. It also increases your total AP so it cant be bad to get.
Nashors tooth is good AP, AS and CD reduction.
Mejais is good to get AP if you own and if not i suggest you take Rylais Crystal Scepter for hp and AP.
Runes are magic penetration and mana.