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TF=trinity force
IE=infinity edge
BC=black cleaver
AA= Auto attack

1. AP nid is primarily a support build, which means your success relies heavily on the team.
AD nid functions as more of a carry, which puts the outcome of the game in your hands.
2. Can take down turrets faster with this build. The whole object of the game is to destroy the turrets, so this is actually an underrated benefit.
3. Opponents are not sure of your capabilities since AD nid is a rare occurrence. Make the most of it by letting the opponent gain some confidence, then move in for the kill when they overextend.
4. Heal can be put to good use. Many noobs forget that the greatest benefit is the AS buff, and end up healing an AP carry instead of a ranged dps. I have often found myself backdooring turrets and the heal is very helpful in doing so.
5. Human form is actually useful. I feel like the only thing AP nid can do in human form is throw javelins while their team is destroyed. Cooldowns can be a pain too. With an AD build, you are constantly dealing high amounts of damage and making yourself useful to your team.

Armor pen. A necessity for any physical carry/dps.

AP- Good for buffing those early game heals so you can survive longer in the lane

Dodge- Any runes can be substituted for these, but I prefer primary runes because the benefit is greater. Nidalee's dodge is pretty decent with a good 29% in cougar form (used to be around 44% when I first used this build, but TF has changed since then and no longer gives 15% dodge).

Completely up to the player. My preferences are listed.

Early game- heal takes priority because heal allows you good survivability in the lane. If the opposing team has a jungler, I recommend getting trap at 3 instead of 4. Better safe than sorry.

Mid and late game- Once heal and cougar are maxed, the other two skills are practically useless, so the order doesn't matter at that point.

Note:I realize this build is expensive, but in the end it will be rewarding.

Your primary goal should be to farm like crazy until you 1)reach lvl 6 and 2) have bought sheen.
Get boots afterwards, if you don't like ninja tabi the alternative should be berserkers.
After that, focus on getting that TF. It will be the core of this build.
Then work on IE and BC.
By this time the game is usually over for me, but you still have two item slots left that should be used for situational items (i.e. banshees, frozen heart, etc)

Nidalee is a very squishy champion, which is why my spells are in mobility.

Cleanse and flash are a godly combination. With nidalee's ability to pounce every 2 seconds, she can easily outrun most champions. Therefore, if you are caught in a bind, cleanse + flash + pounce will save you every time. Useful for both chasing and escaping.

Other options: exhaust or ignite

I strongly recommend these spells. If you decide to ignore everything else in this guide, you should still take cleanse and flash.

Ok. Lets break it down.

Early game: Farm. Farm. Farm. If opponents are harassing you, just heal and continue farming. It is very helpful to take mid because it generates gold faster for you and gets that quick cougar skill point. Do not try any ganking. You will lose gold and experience during your time away from the lane. Being ganked by opponents should not be a problem because you have excellent map awareness with your traps.

Mid game: You should have your sheen and boots by now. This is the time to run around ganking and racking up those kills. You should be able to solo MOST enemies whom you come across, but be wary because smart players will never wander around alone.
When in combat, make the most of your sheen's ability. Combination- pounce, AA, swipe, AA, repeat. Since this is an AD build, takedown will be a strong finishing blow. Do not waste it if the opponent has more than 1/4 of their health remaining, because you will lose the multiplier.

Late game: Now you make the transition from assassin to dps. It is too dangerous to jump into a teamfight in cougar form. Instant death. You should stand back and AA from a distance, then switch into cougar to finish the fight and execute any remaining opponents.

Note: You are AD nid, which means the heal should always be used on yourself for the AS buff(with exceptions). Do not let your team convince you that you should be healing them, because they will benefit more from you killing the enemy team quickly than from a lousy heal.

So thats it. This playstyle is much more difficult to master than the typical AP style, so don't give up if you fail the first time. I hope to post some match history soon to prove that it is rewarding if you know what you are doing.