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.
Hey, this is my first guide, but I do well with it so I decided to share it ^^. I have played Lux ever since she came out, and I love her, but I have taken a likeing to Nidalee too. Well, introduction over, let's get started!
I take Clarity, and Ghost, although, you can go with Flash, and Clarity. Less escape, but more gank. I'd try to avoid Ignite, or/and Exhuast simply because of your root, and slow. Clarivoyance can be replaced with Clarity, but you'll have to return to base more quickly. Revive/Rally you should never go with. Leave that to tanks such as Alistaire, or Nunu. Do not go Smite since you will not be jungling. Teleport might be replacible with Ghost but not recommended, and I do not know about promote.
Put one in Haste, three in Perseverence, and Good Hands. four in Awareness, and two in Utility Master, and one in Insight. Three in quickness, and Intelligence. Then put one in Presence of the Master. Three in Archmage's Savvy. One in Deadliness, four in Sorcery, and then one in Archaic Knowledge.
Pretty flat-out, just follow the guide above, although, i'd recommend takeing the Seals of Clarity, and the glyphs before going onto the marks, and quints.