Okay, so you just picked up Janna, or you want to learn how to roam more effectively? But you don't know what to do and when? This guide will teach you how a roaming Janna support can win a whole game. This guide is highly inspired by the EUW player L9 Ap0calypse, who hit rank #1 on EUW only playing Janna.

Okay, so Janna is not that hard of a champion to play, it is just hard to play her effectively. What the point of this play style is, is to set-up vision in the enemy jungle, and roam with your Jungler, you are not a baby-sitter for your ADC. But, don't leave your ADC in a ****ty lane state. You absolutely can't leave your ADC when the wave is frozen under the enemy tower, and you also can't leave him when he is low HP and there is a big wave crashing under the tower, because the bot-lane and the enemy jungle will just dive and kill him. Every back you need to buy control wards, switch your trinket out for sweeper at around 320 gold on your support item. Sweeper is very important for roaming as you can deny vision to deploy an unexpected gank

You probably want to start with Zephyr this is so you can poke hard early game, this deals quite a bit of damage combined with your Summon Aery

If you are going all-in charge up your Howling Gale for less than 1s, you want to use the tornado around melee range so the enemies have almost no reaction time to dodge the tornado. Using your Zephyr to slow them is also an easier way to hit your tornado more consistently.

Do not waste your Howling Gale when you think you might be ganked or engaged on, as you can use it to interrupt dashes like Leona's Zenith Blade or Alistar's Headbutt

As a Janna support, your job is to provide vision for your team, and protect your carries. This means defensive Monsoon's and sometimes even dying for them. The optimal position for you to be in, is in the back line with your AD-Carry. This is mainly to protect them from assassin's like Zed who can easily engage and disengage.
Your best friends in the mid-late game are your Control Wards, with these you can deny your opponents vision, and help your team with vision of their own. At level 13 and higher you can buy Stirring Wardstone. This item can store up to 3 Control Wards. Make sure to top off your Control Wards every back.

I hope you have learned from my Janna guide, make sure to leave feedback. I'd also appreciate if you would follow my Stream I stream every weekend, from 10 PM CET to 1 AM. I primarily play mid-lane and jungle right now, as I'm trying to get to diamond on those roles. As I have hit diamond on support already!
Thank's for reading this guide and I hope to make more in the future! :)