I thought it was a good guide. I did a guide only a few hours ago, and seems to be pretty clear we think alike when it comes to Janna. I dont necessarily agree with the Banshee Veil, because you and me both know, Janna cant be touched in lane if you push them back enough. The will of the ancients is a good option; Ive never tried it yet, Ill give your build a shot. Check out my build. Feedback is welcome.

Need's an extreme grammar and spell check. Also check out this guide to help you make the guide prettier:
Making A Gudide

Tier 2 boots come way too late. You should only have 5 items so you can ward in late game. Otherwise you're not helpful to the team.

If you have a section of a guide that has only one sentence, chances are that section's not needed and that sentence can be used somewhere else.

If you're gonna support and use 21 in utility and put 4 in Greed , why would you not get the extra gold mastery?