I play support characters a lot and I try out different builds for different characters. Unlike most of the support players especially in Ranked, I actually think about the character I'm playing and build accordingly.
That means I actually try make a build suited for the character, not just stack gold per/10 items and never make any difference which character you are playing.

There are many nice Janna builds on MobaFire and this is just how I play her. Most of the builds don't really differ much, but still there are some slight differences how people see she should be played. All of them are just as correct, but I'd like to share my way of playing her.

Note: I've just found out that all my Zephyr coding comes out as the item instead of the skill. Since it was working properly previously, before the release of the item would someone say WTF do I need to write to get it to display the skill and not the item?

Janna is a skill based support who doesn't require much items. She has a versatile kit of slows and knockups, shield and a heal. Janna is not a healer support although her ulti can heal, but she brings very nice crowd control abilities to the team with her Howling Gale, Zephyr skill and Monsoon.

Janna has low damage since usually people max her shield first, but she's not like Sona. Her main fous is to disable enemies and give kills to your allies or help your allies to not give kills to the enemies. She's swift and her passive Tailwind not only boosts her movement speed, but the allies as well. In addition to that maxing Zephyr second will result in her being a very fast even without shoes. She's an excellent warder due to her natural movement speed and can slip away from tricky situations with her skillset.

Pros:

+ good disabler
+ very fast, therefore an escape artist
+ very good shield which also works for your own turrets
+ shield not only blocks damage, but gives a huge AD boost
+ even tho best as a support, can hold lane alone for a bit
+ doesn't need expensive items to be useful
+ versatile skins

Cons:

- early game very squishy
- full support babysitting can be boring
- don't have a real heal
- seriously low damage
- can't win alone/can't save everyone
- skins in game look like she has broken her hips

• From the Defense tree get some extra HP from Durability and Veteran's Scars
• Some extra armor and magic resist from Hardiness and resistance]], one of these can be exhanged into Summoner's Wrath when using Exhaust.
• Summoner's Insight and Mastermind for shorter cooldowns on your summoner spells
• Meditation and Expanded Mind give some extra mana in case you have mana problems, but one of these can be changed into Wanderer if you prefer the movement speed instead. In my opinion Janna is fast enough without it, but if you use your skills often you can go quite easily out of mana so these are good.
• More gold from Greed and Wealth . Some people don't like Wealth because it gives only 50 extra coins, but I think it's very nice so you'll get an extra ward or extra potions at start.
• I get Pickpocket for auto attack harassing. If you can't land auto attacks at all, you're doing something wrong.
• Nimble makes you even faster.

• Greater Mark of Attack Damage runes are great for harassing with auto attacks early game. Can be changed into Greater Mark of Armor armor runes.
• Greater Seal of Armor runes provide you the necessary armor needed when laning bot lane against a proper AD carry.
• Extra magic resist from Greater Seal of Magic Resist runes is useful throughout the game, but CDR runes are also very much usable. I just prefer defense since you get much CDR from items eventually anyway.
• As a support you don't farm so you'll benefit from extra gold income through Greater Quintessence of Gold runes.

Flash is the standard spell for almost every hero without a proper escape mechanism and even though Janna is an escape artist, she makes a good use of Flash. You can either use it to initiate with Flash+ Monsoon combo or just to escape from a bad spot.

Exhaust is useful throughout the game against an ADC and other AD based characters. Slows and reduces damage for a short time. Usually I'd pick this.

For more offensive kill driven game Ignite is a good pick. It's also good pick against an enemy team full of healers or if nobody else in your team picked it. I'd still prefer Ignite.

I like Heal and it was good on a support early S3, but now it's just as underrated as it was in the previous season. We'll see about it's uses on S4.

Janna's passive is what makes her so great asset to the team, it increases allied movement speed by 3%. So if you know your team will have slow characters, Janna is a good choice for support, or if the opposite team has speedy characters like Master Yi which will give your allies a slightly bigger chance of catching up on them or running away from them.

Howling Gale is your main disable skill, which either allows you and your teammates to catch up to enemies or helps with escaping. This is the last skill to level up, because you should only use it do disable. Fully loaded it does nice damage so be careful not to hit minion waves with this unless you're intending on pushing.

During laning phase you're babysitting your carry mostly with this skill so they won't take any harassement from the enemy and that they may harass. Eye of the Storm is an epic mana eater so I wouldn't spam it just for easier last hitting, but in cases like laning with a Caitlyn or Vayne this skill works very well with them if you want to harass the enemy and eventually pick up a kill for your carry.

I don't know if this skill with display a wrong picture, but if it does I'll explain here: Zephyr slows down 1 enemy with higher slow each level so I'll always level it up second after Eye of the Storm. Janna also gets passive movement speed while this spell is not on cooldown, so it makes her a very fast mover.

Monsoon knocks back enemies and heals Janna and everyone in the effected area while channeling. It's a useful ability to interrupt, but it also heals very nicely. It's important to time this skill well, because with people like Amumu and Kennen you don't want to be kicking off enemies their ulties. Hoever when timed right ((Monsoon]] is a very nice spell to relocate enemies either by kicking them off you or by pushing them right towards your enemies.

I'd prefer the 1st way to start with Janna for some sustain in case you get harassed. You'll have nice wards to take care of your lane vision until you get enough money for Philosopher's Stone and new wards (520g Philo +150g 2 wards).
The second way allows you to get your Philosopher's Stone faster (which I take as a core item, because of the sustain and gold/10 you get) but you'll lack some sustain and wards, but however you'll be able to get more wards when going back earlier.

Some people don't understand why I rush Philosopher's Stone so here it comes: it gives you a nice sustain and decent gold/10 amount which allows you to get money and therefore wards faster as well as other items. Some people rush Sightstone, but I rush Philo for faster money since separate ward are ok early game.

My preferred core build

Philosopher's Stone

This is how I build most of my games as Janna. I rush Philosopher's Stone, get a Ruby Sightstone and then build a Locket of the Iron Solari unless my jungler or top laner builds it first. I keep Philosopher's Stone as long as I can for the extra gold/10. Ionian Boots of Lucidity are good for CDR and since Janna is fast already as it is, I don't build her Mobility Boots which are very popular with supports, but they're ok boots.

Full Build example

So this is where some people complain 1 space should be left for wards which is ok, but in case you run into a very long game and get enough money I'd buy all 6 items. What comes to Season 4, there will be a 3 ward limit anyway so it's ok to fill up even the last space.
In addition the core items you can either upgrade Philosopher's Stone into Shurelya's Battlesong to chase/escape enemies or use the nowadays very popular Mikael's Blessing for the nice healing/cleanse active and extra mana regen.
Last space is either for wards or usually I build something from Kage's Lucky Pick. Mostly Shard of True Ice works well with melee initiators like Jarvan IV/ Xin Zhao etc, but the other options are also relatively ok.

Boots:

15% CDR is always welcome on Janna, but she can manage without Tier 2 shoes for quite some time.
For CC reduction and extra magic resist Merc Treads are great.

Aura Items:

Aegis/Locket gives a nice magic resist aura, some armor for yourself and an active shield that is far better than people think. Core item I'd say.
Gives a mana regen aura and an active slow that works well together with Janna's own slows, but also helps mana hungry teammates. Shard of True Ice also provides stable 4 gold/10 regen even as an upgraded item.
Not the best item for Janna, but it's ok with teams who need some spellvamp and/or extra ap.
Decent item, but costly and most likely bought by an AP carry so not as beneficial as other items.
Frozen Heart lowers the attack speed of enemies and gives lots of armor and 20% cooldown reduction, so it's a very good item against heavy AD teams.

Active Items:

Most basic support item built from Philosopher's Stone, has a speed active and gives stable regen for HP and mana.
The other item built from Philosopher's Stone, Mikael's Blessing gives quite high mana regen and an active single target heal. If you have mana problems and you feel like you'll be needing a heal, then go for it.
Twin Shadows is built from Kage's Lucky Pick, it gives movement speed, little bit of AP and some magic resist so it's a very well balanced item. It also gives an active ghost slow, which means ghosts will scout your enemy for you and slow them allowing you to get closer to them for some more CC. Works very well on Janna in all of it's parts.

Thanks for reading my guide for Janna, the maiden of the wind. I know there are many guides about her in Mobafire, but I hope this was useful to you.

Other notes:

I'm well aware of the Zephyr issue in case it still shows the weapon, not the skill, but I don't know how to fix it so please don't complain about it.

I know I haven't been updating my Janna guide (or the other guides) very often, but I've been busy with my personal life outside the internet and the remaining time I've spent trying to climb into Platinum. When season 4 comes I'll be sure to update the guide up to date after playing a few games with Janna.

7/11/2013
- Edited item build
- Changed masteries and other stuff

7/5/2012
- Edited Item build section and added Items section
- Edited chapters order a bit - nothing major

13/1/2011
- Corrected the BBCode error in Skills section, obviously you can't cursivate and make a list at the same time with them both working
- Made Summoner Spells section
- Added Babysitting sub-section to Your role in the team -section

29/12/2011
- Quick edit on the runes, because I facepalmed hard when I realized all my runes were marks -.-
Note: More editing oncoming when I'm not semi-drunk and tired.

22/11/2011
- Edited Masteries to fit the current mastery tree and rewrote the masteries section
- Switched Item build slightly and removed first build
- Rewrote Runes section to fit the new runes I gave to her
Note: I'll be editing this guide further and make a separate section for Summoner Spells and add a sub section to Your role as a support -section concerning gameplay