Only way I can think of is with dialog set rotation. You're going to need a custom image in the form of a circular sector with quite a small angle. Probably going to need a number of duplicates of the said image as well so you can make them fan out as the circle "fills" up.
@DarkRevenantX: Go
Don't think flash supports been added yet, unless Blizz added it discretely.
@Edicitsep: Go
Assuming you're using photoshop, you may need to play with alpha channels to accomplish transparency.
@Edicitsep: Go
Only way I can think of is with dialog set rotation. You're going to need a custom image in the form of a circular sector with quite a small angle. Probably going to need a number of duplicates of the said image as well so you can make them fan out as the circle "fills" up.