So I love playing support and i have played Taric, Soraka, and a little of kayle support (which I do not like that much). But i just played Janna and i wasn't very good but i don't understand her support i mean she can protect team and slow enemies and her whirlwind can knock up but her only true heal is her Ult. To me it doesn't seem a good support maybe i haven't played her enough or just don't know what I am doing as Janna but it was a thought.