Not Updated For Current Season
Sorry for my poor english,
This build is very simply and for a Offensive Janna.
First check the sequence skill with Howling Gale and ZEPHIR, level 5 choose EYE OF THE STORM and level 6 Monsoon. Repeat this at level 18.
I choose this items because you have heal and life steal and lot of ability power.
In Summoner Spells, choose HEAL because in 1vs1 you have the last hit with ZEPHIR and TELEPORT for first back with first item.
Just test him and vote this.