Janna Build Idea

So I main Janna, have half a million points on her and mastery 7, but for the most part I've only stuck with the more traditional builds. So I was wandering, would Tear of The Goddess be a good item on Janna? I mean, you could fill it up rather quickly since you're constantly shielding somebody, not to mention the increased mana regeneration and the refunds 15% of your mana spent would be great on her considering that, except for her W, she has very high mana costs. Overall though with support champions you build more mana regeneration than actual mana so I feel like it would be somewhat wasted once I upgrade it to Seraph's Embrace. I don't know, those are just my thoughts.