Janna

Strengths

Eye of the Storm can be used on allied turrets.
Quickly firing a Howling Gale without the charge up can be used to heavily disable the other team.
Timing Janna's ultimate can push enemies away from a wounded ally or even separate enemies.

Passive · Tailwind — Janna's allies gain Move Speed moving towards her. Janna deals a portion of bonus Move Speed as bonus magic damage on hit and with Zephyr.
Q · Howling Gale — By creating a localized change in pressure and temperature, Janna is able to create a small storm that grows in size with time. She can activate the spell again to release the storm. On release this storm will fly towards the direction it was cast in, dealing damage and knocking away any enemies in its path.
W · Zephyr — Janna summons an air elemental that passively increases her Move Speed and enables her to pass through units. She may also activate this ability to deal damage and slow an enemy's Move Speed.
E · Eye Of The Storm — Janna conjures a defensive gale that shields an ally champion or turret from incoming damage and increases their Attack Damage.
Ultimate · Monsoon — Janna surrounds herself in a magical storm, throwing enemies back. After the storm has settled, soothing winds heal nearby allies while the ability is active.

A suggested 5-lane lineup built around Janna, based on hero partnerships and role synergy — not win rate.