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...

Hey man, tried this build out in my first QM with Kael'thas, only been playing a few days, and it went really well for me. Of course my numbers weren't that high because I haven't been playing too long and I'm not too experienced with him yet, but I will get there! Thanks for the awesome guide!