As we see on the screenshot above, After Effects CC 2014 by default only applies the mask to the original layer, instead of final blurred image, resulting at a fuzz edge phenomenon when rending layers. I like to know how we can mask the final image with effects applied.
My current solution is to put another layer on top and mask out that layer. Unfortunately when completing complicated motions such as resize and moving, it becomes a complex task to make sure two layers synchronize.