Hi everyone. Here is my janna build. I hope u guys will like it and it can really help u.

There are those sorcerers who give themselves over to the primal powers of nature, forgoing the learned practice of magic. Such a sorceress is Janna, who first learned magic as an orphan growing up admist the chaos that is the city-state of Zaun. Janna eked out what living she could on the streets. Life was tough and dangerous for the beautiful young girl, and she survived by her wits, and by stealing when wits weren't enough. The rampant magic that characterizes Zaun was the first and most alluring tool which Janna realized could both protect and elevate her. Janna discovered that she had an affinity for a particular type of magic - the elemental magic of air. She mastered her studies of air magic in a matter of months, almost as if she was born of it. Janna went from a street vagrant to an avatar of the air virtually overnight, stunning and surpassing those who taught her. Such a rapid ascension also changed her physical appearance, giving her an otherworldly look.

Seeking to right the injustice in the world (particularly the insanity that has become the city of Zaun), Janna has brought her talents to the League. She is a voice for the regulation of magical experimentation and a supporter of the development of techmaturgy, making her an indirect ally of the city-state of Piltover and the amazing techmaturgical minds that live there. Janna is also a new favorite of the League's many fans. She is often the center of attention at functions, fan appreciation days, and other celebratory events. There is something untouchable about Janna, however, and her affections can change as quickly as the wind.

Do not be captivated by Janna's beauty. Like the wind, she is one gust away from terrible destruction.

U will start with Faerie Charm, Health Potionx2 and sight wardx3
remember to buy some sight ward everytime u go b. I usually keep 1 slot sight ward.1 slot = sight wardx5

Alternative Boots

why not [ionian boots of lucidity ?

will be useless in my build, coz i have Deathfire Grasp and Shurelya's Battlesong. Ur cdr will reach 40% when adding wif mastery and runes .
Why i use Boots of Swiftness?
Its because u will need it to run away.
Wif Boots of Swiftness, Flash, Shurelya's Battlesong, Eye of the Storm, Monsoon, Zephyr and Howling Gale, u wont die easily. Therefore u can stack Mejai's Soulstealer easily.
Those 5 items are the core, u can buy the following items to complete ur build.

It is always good to ap character. The passive can let u deal heavier damage. But in my opinion, u dun need it coz u r a support. Btw all is up to u.

U can use it if ur team have a fed ap carry or ur team have more ap champion then ad champion. The ap and spellvamp aura is good.

When combining wif Zephyr, U can slow enemies extremely hard.

U can use this to lower their magic resist for ur team. If they deal too heavy magic damage and can easily focuss u, it can help u.

....
Base on ur preferance.
U can also change the order of Shurelya's Battlesong and Zhonya's Hourglass.
U can sell Chalice of Harmony when u have Deathfire Grasp.

I will use it only for escaping or disabling enemies. Therefore, I max it lastly.

This is ur bread and butter. U use this to harass enemies or last hit minions(mainly not). I will max it first. It deal really horrible dmamage. It passively give u move speed.U can use it for running away or chasing enemies for ur teamates for an ace. (after teamfight)

I will max this after Zephyr. It can support ur teamates or even turrets. U should shield teamate in this order:
a dying teamate-> AD Dps-> Ap carry-> urself->Tank.

It can help u and ur teamates a lot. It can push enemies away from a wounded ally/turret/inhibitor/nexus or even separate enemies. U can use it as an area control too.

U can use ur Howling Gale behind turret. Hide ur Howling Gale under turret. Using it also in brushes, can prevent enemies from dodging it. As a support, u must not farm too much. Let ur partner farm more.
Also, u should lane wif an ad carry.

As ur job is to support, u have to stand behind all ur teamates or a save place. Then u should spam as much ability as u can. Therefore, U dun need to charge ur Howling Gale.Use ur active of shurelya reverie, Howling Gale Zephyr and Monsoon to chase enemies or retreat to turret or base. Flash then Monsoon can push an escaping enemy towards ur ally. This is just like the Fling of Singed. U can use Howling Gale, Monsoon or even Zephyr to prevent enemies fromgoing to a teamfight, usually, i will choose to prevent their carry or tank to go into the teamfight. If u do that, their team must call u *****.

U can press [alt+e] to quickly use ur Eye of the Storm to shield urself.
Use ur Clairvoyance when ur team r chasing enemies, especially when they suddenly go to brushes,Ur team may get trapped.
Use ur clair voyance when an enemy has only little hp but ur team cant chase him(he is under turret). It's because he may be recalling under turret, Clairvoyance can let ur teamates( Ashe, Ezreal, Pantheon) use Enchanted Crystal Arrow, Trueshot Barrage, Grand Skyfall.
Use also Clairvoyance to the brush if someone go in wif low hp to recall and no one is fast enough to go to kill him. Its because minion is op lol. U may use minion to kill him, especially early game.

i feel sry about that my english isnt good ,hope u guys wont find it difficult to read my guide .

This guide MAY be updated after every new patches

If you have other suggestions please tell me, I would like to improve my guide as much as possible.

And here is my shaco build. It is very detailed. It teaches u how to build shaco in different way.

http://www.mobafire.com/league-of-legends/build/1hit-jungle-1hit-ap-as-onhit-ad-normal-jungler-updated-148939