What's Janna exactly?!

Before Season 4 you could play her as AP mid, but after recent nerfs I don't recommend doing that. Janna should be played as support.

She is very good babysitter with tons of kitting abilities. Plus, Janna can disable and control the positioning of the enemy team.

Take Ignite, Heal or Exhaust and Flash.

Ignite - because Janna brings tons of CC and almost 0 damage to your lane.
Exhaust - if you play againts an assasin.
Heal - new heal counters ignite and can help you escape from ganks. Atm this spell is my favorite one.

Recommended:
9x Greater Seal of Scaling Health
9x Greater Mark of Armor
9x Greater Glyph of Magic Resist
3x Greater Quintessence of Mana Regeneration

You can change Quints if you like. I just don't recommend taking magic penetration - kinda useless stat on new Janna. She isn't damage dealer!

Offense:
+5% CD and +1% damage ( Expose Weakness ) for your carry's

Defense:
Early tankyness is allways better choice than Gp5. Plus, Oppression mastery is very good on Janna.

Utility:
Don't go deep into Utility tree. Why? Because in LoL it's everything about early game. Defense is the way to go. Take Meditation tho.

Max Eye of the Storm first for bigger shields.
W (Zephyr) for more slow - second.
Take Monsoon at 6.
Howling Gale costs tons of mana and do like literaly 0 damage after nerf - max it last.

There are two ways building Janna: tanky or with Tons of AP (preferably). In both cases you should go for 40% CDr.

Tanky Janna is kinda useless - no one will focus you anyways. So buy AP (mainly for your Eye of the Storm) and shield carry's (adc preferably).

Atm i would recommend rushing Zeke's Herald. In my opinion this item is really underrated. It gives you 20% CDr, 250 Hp and aura for your team (especially for your adc). Just look to the stats:

The base stats are 97.3% gold efficient.

The item is

142.6% gold efficient while the wearer is standing nearby 1 allied champion. The item is 279.2% gold efficient while the wearer is standing nearby 4 allied champions.

And it has 60-69% win ratio in ranked games.

If you want Gp5 item, buy Frostfang. Other option - Nomad's Medallion. It's okay choice too, but i don't like upgrading it. Janna doesn't need speed boost for the team with her kit. In my opinion you can invest this 1135 gold into AP item like Morellonomicon (more mana regen, same amount of CDr, AP and not too bad passive). Banner of Command or Athene's Unholy Grail could be replacement for Morellonomicon.

Atfer that build Rabadon's Deathcap or other supporty-AP items like Frost Queen's Claim, Twin Shadows, Ohmwrecker, Banner of Command.

Early game - Janna is aggressive support (most of you didn't knew that for sure), but only if adc is playing like that. This is why i like playing with Lucian, Graves, Caitlyn. She is master of escaping from hopeless situations. This is why you can push your lane realy hard. Oponents will need at least 4 players to gank you successfully after level 6. This is why Janna is perfect support for SoloQ games, where your partner can be realy tough to play with.
The best counterpick for Janna is sustain or hard poke champs like Sona, Lulu, Nami. A good Leona, Tresh or Blitzcrank can be pain too.

Mid game - If your adc is fed enough, you can leave him alone and start roaming.

Late game - this is where Janna shines. In teamfights your job is to shield and protect carries, in the meantime CC'ing the **** of your opponents.

Remember:
Janna can stop some ultimates!
Janna is a very good bait. Don't chase her to unwarded bushes! :)

A beginners guide to support Janna:

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Ranked game with Janna as support (Some perfect ult examples!!!):

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