This is actually kind of what I thought of too! My thing is making support characters into support/damage! Just a suggestion to add, Storm Shield at level 20 would be beneficial if your team lacks the bulkiness of a tank or two or a second support. Other than that, I like it.

One thing that I will note on: most of your damage comes after level 16.

Also, I would take harmony at level 1 so you don't get mana screwed. If you think you can survive the enemy team, then I would stick with your setup instead, just be aware of your health/mana. Of course again, after level 16, mana becomes nothing when you can get through enemies easy with your W and don't even have to heal. It's just a matter of preference + situation for that, I guess.