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.
This is my First Build.
This is a build for AP Nidalee that works extremely well for me. It gives you tons of damage with your Javelin Toss and tons of heals from Primal Surge.
The Summoner Spells I take are Teleport and Clarity.
Teleport because its useful for saving allies, if you can get there fast enough, and for saving towers from minions and even other champions as well.
I take Clarity because in my experience Nidalee is very mana hungry before I get my Archangel's Staff, and Clarity allows me to stay in the lane or even in mid for longer periods of time.
When you spawn buy an Amplifying Tome and a Mana Potion. The Amplifying Tome gives you a slight boost in damage and healing early on that can be essential. The mana potion is there so that you can put off using Clarity for as long as possible. Early Game you want to be careful until you have judged your opponent(s) to be smart, stupid, or have never played as or against Nidalee before. I typically seem to find the second and third options and that makes me pretty happy. As soon as you hit level 6 you have a mana free way to farm for gold, Aspect of the Cougar, particularly when there are large minion mobs near your turrets because you can kill the mobs and then simply heal yourself up. This will allow you to get your Tear of the Goddess. Aspect of the Cougar allows you to charge this up without any mana costs as you can spam the Cougar skills without a problem.
By this time you should have a Sheen, Boots of Swiftness, and an Archangel's Staff or close to it. You may have even started on your Zhonya's Ring. By this time your skills are sufficiently powered up by the ability power that you can one-shot minions with you Javelin Toss, and take out large chunks of squishy carries' health. Your Primal Surge can be the difference between life and death for yourself and your allies. Usually the game ends around this point for me item wise.
By this time you should have Zhonya's Ring, a Nashor's Tooth, and possibly the Void Staff if you were fed enough. By now Cougar form should be destroying any enemies who think they can take you in close combat without stuns.
I'll add other things to this and change it as I get constructive criticism from the community. This IS my first build I've posted on mobafire so don't totally bash me.