You might want to take another look at Deathfire Grasp since it is going under some changes. Also Rylai's seems redundant considering Janna already has a slow. With that being mentioned, I also find your + Armor runes unnecessary since you can probably outrun most champs given the W + Q combo.

I would like to see your reasoning for picking Clarity over other summoner spells.

I love how you -4% CDR in the offense tree. I give Janna the same mastery when I'm playing her as a support since I find my skills often to be down just when I need them the most.

I actually like this build. I don't know that you shouldnt also get philo stone. Wouldn't it stack as well and build into your shur rev?

I actually like this build. I don't know that you shouldnt also get philo stone. Wouldn't it stack as well and build into your shur rev?