I like it! I like it a whole lot!

...but I'm wondering about the effect its going to have on the setting. In my mind, the goal to "protect the world from the things that threaten it" is something the players should be able to do, and in my experience it's unwise to overshadow the PCs in any way. The world may be full of big, powerful people, but for whatever reason the players are the ones who get to be the heroes.

Maybe the big dudes are old, and no longer able to save the world. Maybe they don't care about the fate of the world, preferring instead to delve into their own mysteries and projects. Maybe they just can't come together on anything, and that's the only thing keeping them from doing real good in the world. No matter what, at the end of a campaign these huge, mythical figures need to be the ones patting the players on the back, not the other way around.