I have been playing Janna since she has been a top laner back in Beta.
this build focuses on the strengths of the guardian tree and the use of aoe shred/ardent buff.

many people will look at this build and just see some troll AD build. if you're a competent Janna player, and you're a bit aggressive this is the build for you.

you can use guardians shield by simply walking near an ally that is taking damage or shielding an ally and taking damage, this will give you a small sprint buff and a 60-200 hp shield for you and the lucky ally of your choice. you can then apply your shield after for even more enemy tilt.

once you have your Ardent cencer you're going to want your frozen mallet asap. i get sight stone first though. zombie ward helps with ward longevity so you want to pump out as many wards as you can to get those free wards up. HOWEVER once you have that frozen mallet, any target you hit will be effected by Font of Life, which will heal any ally who hits that target and give them your Ardent cencer buff, i then go Ruuans hurricane if my team is winning to help spread the frozen mallet slow to more targets in team fights. (yes you will be utilizing your auto attacks at any given chance you can). If we are on the losing end i go for Black cleaver first to get more health.

this is a build for aggressive players who want to actually have a lane presence.
this build WILL NOT automatically make you dodge skill shots thrown at you. that's on your end.!

Compare this rune set up to an Aery set up after your match, you'll see much better numbers with this one. I promise!

hope you enjoy the build. GL HF