Hello,

this is my Janna full supporting guide. It contains: Item Build, Masteries, Runes, Summoners Spell, Skill sequence, 'supporting rules', where u have to put your wards and much more!

Although this is my first guide so please be gentle and nice with me :)
This is, by the way, how I always play Janna and my team mostly liked it that way ;)

As runes I use usuall AP-Caster Runes. Because ability power and mana reg is something every supporter and Ap champion need. Magic pen is also a normal and needed rune.

The Masteries I use are:
"3/6/21"
It's just nice to have the 3 Points in attack to give u a 'lil boost of ability power every level.
The 6 points in defense will help u, to last a 'lil longer - because you often be the target which will be focused. Because your enemys will think, that you are the one to get killd as fast as possible.
In fact Janna is an Support Character, so most of her Abilitys will scale Ability Power, that's why I set the 21 Points in Utillity. Through this u get, mana reg, life reg, maximum mana increased, reduced spawntime, 1 GOLD every 10 seconds('cause you're not allowed to farm), more exp('cause a supporter is always on a low lvl), lowered cooldown on all your abilities and summonerspells. Works well. ;)

Best Choices:
It's nice as a supporter because you can join an teamfight easily or help a teammate. You're there and support him by just jumping through a wall or something.
Best supporter Spell. You can see a part of the map and if you don't have a ward it's sometimes a lifesaver - just like flash. A nice strategy you can use with CV(clairvoyance) is that you use it at the beginning of the game. You can see what the emenys buy if you use it at 00:03 or 00:05 and set it to the shop of the enemys. It's a big help and you can tell who is going on which lane. Or you can see where the enemy jungler is starting his jungle.
Some Summoner Spells you also could choose:
Also good to support to give you and your team mana. But I do not like it that much. Because your Soul Shroud will give you a nice mana reg.
The name of this Summoner Spell explains itself. No further explanation needed.

So here we go to the part I like the most. The Itembuild. Im Just gonna tell you what you must have in the phase of the game. With phase I mean: Early, mid and Endgame.

Early Game

Philosopher's Stone This is one of the best early Supporter Items. It gives u every1 10 seconds 5 Gold, a high mana and life reg. So perfect for the early game.
Same Thing as Philosopher's Stone. 5 Gold every 5 seconds and 350 Life.
These boots lower your cooldowns. You could also call them: "Boots of the Supporter"
Sight Ward ALWAYS. REALLY ALWAYS have 2-3 with you.

Mid Game

Very nice supporting item. 520 Health and 12, 5 mana reg every 5 seconds for you and your team. Also reduced cooldowns. Important item.
Also a needed supporting item. Attack, armor and magic resist boost for your whole team and for you. Also you're the only one who gets life.
Sight Ward Just like Early Game but now have 4-5 always with you.
An Item you should start getting in mid game. To see Wards or stealthed Enemys.

END/LATE GAME

A true lifesaver. You really should get this one.
Ability Power and spell vamp for your team. A MUST HAVE for your AP Champion and also for you, too.
Sight Ward Now it's the point where u can get them if your item build isn't full and you still have place left in your inventory.
Nice Item. Slows enemy's near you. Cooldown reduction and lots of Mana and Armor.


Wards are more import than any item!!

Supporting Rules or how ever you want to call it. Your job is it to support your team. In any kind of way. Die for them, protect them, save their ***es, ward the enemys jungle or your own - Whatever is needed to be done.
In the early game you usually go on the botlane with your ad carry. Like Ashe or Caytlin.YOU ARE NOT ALLOWED TO FARM WHEN YOUR CARRY IS ON YOUR LANE! But if he's not and your alone on your lane feel free to farm.
If your teammates get attacked and need to fall back and one is close to death, use your flash to get to him. Use a cc spell on your enemy (Janna should use q.) So u can save him. Even if you die then, it was worth it because one of your teammates who is able to kill a target easily has survived. You're like a babysitter of the whole Team. So never walk around alone, always have atleast 1 Teammate with you.

In a teamfight try to stay between your ranged and meele Teammates. So u can support all of them easily or save them if needed. Don't killsteal or kill. You're just allowed to kill if there is no chance anyone else could get him quick.

And Just like I said in early game where your ad carry is you have to be, too. In mid and late game try to be where ever you're needed.

Try to have as much MAPCONTROL as possible in early/mid/endgame.

Like I said in the chapter "Supporting Rules" do not farm as long as any of your teammates are on your lane. That's why you need to get "Philospher's Stone" and "Heart of Gold" as fast as possible. So that you still can get the gold you need. Don't attack your minions too often. Maybe that destroy's the farming of your ad carry. Only if he says it's ok you can do it. But only to get them on low health.

This Map will help you where you can set up your wards.
[http://imageshack.us/photo/my-images/835/warding.jpg/]

Wards are more import than any item!!