Not Updated For Current Season
I find this build to be the (all around everything) kind of build with Nidalee, because it gives health, a nice slow, and bonuses in AP or AD for EVERY ability she has.
QUICK DESCRIPTION: Nidalee is a Gank champion, You wont want to go Toe-to-Paw with champions like Warwick or Master Yi, you can avoid them if you like, but remember that if you can always escape in the bushes if you feel outmatched. since her ultimate increases her Cat Form damage, it is a good idea to go mid
EARLY GAME: try to pick at them with your regular attack, your movement speed should give you an edge (see item build) only use Javelins when you have a clear shot, and at a far distance.
ROTATION: You can do this anyway you want, but I like to run at them without using pounce right away, unless they are ranged, in which case you'll need to pounce. I use Swipe then Takedown,because Takedown does more damage the lower their health is, and has a shorter cooldown, so it will be back around the same time as Swipe this way. After that I will Pounce away from my target, switch to Human Form, Heal, toss a javelin, and Trap(if you think you can get em with it), then switch back to cat and repeat. this is much easier and feels more fluid as you get cooldown reduction, so go for golem when you can.
Pro-Tip: Remember that if there are no wards in a bush, when attacking from that bush, you will ALWAYS hit first on the person trying to kill you (because they cant target you). this means you can use Takedown and Swipe, and then use Pounce to get away.
RUNES: Many people aren't used to not having health for their runes, if you feel this way, get some health for your seals, and start with some mana regen rather than boots.
Marks- Magic Pen is ideal for this because almost all of her abilities (except Takedown) are magic damage, and you may not want to deal with getting magic pen boots, because you'll need more movement speed than that
Seals- I went with Mana Regen, because if you are conservative with your mana, you'll be good on mana until level 6, in which you can get Cat Form, and then mana wont be too much more of an issue.
Glyphs- I chose Cooldown Reduction per Level, because cooldowns are a nice touch with Nidalee, since her pounce is 3 seconds and her other Cat Form abilities, are around 5, you only need enough cooldown reduction to get those to be 3, for the most damage output, so also try to go for golem if possible, i chose "per level" Glyphs, because you only really need the cooldowns at level 6 and beyond, in which case the cooldowns will almost exceed the non "per level" counterparts.
Quintessences- I chose Movement speed, because, Again, Nidalee is a Gank champion, and since she can't stealth, when you run away, you'll find yourself being chased a lot.
Pro-Tip: When being chased try to go into bushes, you will move faster, and it is always fun to try to kill your assailant.
ITEM BUILD: While you maybe be wondering why I chose this build rather than the "Trinity Force" build everyone else uses, it is because while any straight up AP or Trinity Force, or AD builds there are, none of them give this many bonuses to this many abilities, in such a great way. All of her abilities stack with AP except Takedown, since you'll have lichbane, you get the AD that you need for it From AP, and since it is easier to get AP than it is AD, you even get more damage out of it than a straight up AD build would give.
Boots of Speed + 3 Health Potions- The movement speed is what makes you better than most champions in the early game, because you can run in, hit them, and run right out, or if up against a melee, you can keep running back, turn and hit, and then run, when he gives up and runs away, you can pick at him 'till he goes back to turret or minions (I've been insulted so many times for doing that in-game). the Health potions are to keep you out and about for longer, and to save your mana for javelins, rather than heal.
Sheen- This is part of a Nidalee's staple diet. Every Nidalee build does, or should incorporate this item. It will give you a small boost to your damage from Takedown, or just help with an extra hit after a Javelin Toss early game.
Boots of Swiftness- As Nidalee, Move Speed is a good thing, you'll need Swiftness Boots to get ahead (or further away) from your enemies. and since you are a gank champion that cant stealth, you will be chased alot (as I said before) so you will need the Swiftness Boots or else you will be hit in combat, and slowed down if you were to get Boots of Mobility. "Remember, you don't have to be faster than the Crazed Splicer, just your Neighbor!"
Lich Bane- You'll need this Item early in, because if not the AP you build afterwards wont be worth as much. There isn't much to say about this item, except that it is expensive, so yes, building an expensive item early game isnt good, but since you're buiying sheen, you aren't going that much out of your way, besides, it gives some nice bonuses.
Guinsoo's Rageblade- After building something as expensive as Lich Bane, you will need to get something that will make a noticeable difference, but also cost very little, while just over 2k gold, this gives tremendous bonuses. Since Nidalee's Pounce Is a decent means to get around, and it's cooldown is only 3 seconds, you can use pounce to get the Passive of Guinsoo's and keep it at 8 stacks for good, meaning essentially that Guinsoo's Rageblade, for only being 2k, will give you 35 Attack Damage, 93 Ability Power, and 32% Attack Speed. not bad.
Rylai's Crystal Scepter- This item is good, because Nidalee will need some health down the road, and this is where you'll get it. It also gives Ability Power, and a slow that triggers with each ability hit on the target, I like this because, after you use your Cat Form rotation, it makes it easier to either escape, or chase, whoever was the victim of your attacks. making your job easier. not to mention, In a 1v1 fight with any champ, this makes it easy to use your abilities, pounce away, and Heal before going back in, maybe even toss a Javelin before you do.
Zhonya's Ring- This item speaks for itself, you want ability power, ability power makes you big and strong. so 120 ability power plus the passive, makes this Item a no brainer, i have experimented with using two archangel's staves instead of the last two items, i concluded that it isn't necessary, and that Nidalee doesn't really need the mana that it gives.
Hextech Gunblade- I like this item because it gives 75 Ability power, which is nice for an ability power item, and some extra attack power, meaning that it gives 75 ability power for your abilities, but an extra 135 or so, for Takedown, thanks to Lich Bane. Essentially, you could use any item for this slot, from Frozen Heart, To another Zhonya's, I chose this Item because it gives nice bonuses, and a big boost to Takedown, while having some lifesteal and spell vamp to help you regen when killing minions or something, just to save some mana, also, it's active is very useful when making a kill, or just dealing some damage before your rotation.
A Couple Spells I use:
Cleanse- I like this one because, as Nidalee, as I've maybe stated a thousand times, you will be chased, you aren't Shaco, you can't go Invisible and safely run, you have to have yourself a serious dogfight. that being said, you never know what champions the enemy will pick (unless you're doing ranked) so you will want to pick this up for the CC they may have.
Flash- this one sort of goes without saying, because i already stated that you will need to escape. so what better way to escape after a rotation, than flash?
Pro-Tip: Flash doesn't always have to be used defensively, use flash when you want to pick someone off in a team fight, or use it shortly after turret diving, for a quick escape with minimal bodily harm. also, if you use pounce and then flash while mid-air during the pounce, you will land on the location that you flashed to, meaning that if someone is far away from you, or it is someone like Ryze, that you are sure will snare you. you can always pounce-flash right on them and deal the damage you would from the landing, followed by the rotation.
(its actually really funny to watch, because it happens so fast, that you look like a total pro when pulled off correctly.)
Spells You Could Use Instead:
Ghost- Movespeed is a must for nidalee, but if you want to swap out a spell for her, you could try swapping Cleanse for Ghost, Maybe even Swap Boots of Swiftness out for Mercury Treads, and only use ghost when you need to get away from someone faster than you (which there shouldn't be many of)
Ignite- I always liked Ignite, it is useful for the early game kills. Nidalee needs an edge over people, an edge she will get if she kills people early game. I like ignite because its a fun thing to use as you are getting out of a cat rotation, and keep enemies in combat so that things like Garen's or Miss Fortune's passives wont activate before your rotation is back.
Exhaust- Not Absolutely needed, but its good to have, its good for if you have someone you need to catch, although i wouldn't use it that way. You can use it when up against that one highlandering yi that build a bunch of phantom dancers so he speeds ahead of everyone, you can use it to make him not hit you, and stall some time for when it turns off, if he speeds ahead of everyone else, when his highlander turns off, he is your PREY.
Spells You Shouldn't Get, And Why:
Teleport: You Could use this, But I wouldn't because your build involves so much movement speed, that it isn't much of a hassle to get to where you need to go.
Heal: not only is this not needed, but its complete garbage on Nidalee, her heal will suffice, and not only that, but late game, her heal will cover about a third of her health, much more than the long cooldown Heal spell. Only use this if you feel its necessary for your teammates
Rally:This is completely unecessary, again, like heal, only use this if your team wants you to. the only thing i could find this as being useful for other than that, is if you want to take down a turret quicker. but even then, its not worth wasting a summoner spell over.
I went with Utility mainly, because of its cooldown reduction move speed and mana regen, it pretty much just tacks on more things to reinforce your rune page, for the secondary part of the runes, I found Offensive to be a bit more useful. with its cooldown reduction and magic pen, it seems perfectly fitting for nidalee.