This technique can be used with any filter or multiple filters between Mask: Simple Shape and Mask: Apply to blend the filtered image with the image immediately prior to Mask: Simple Shape. For example, you could have color correction before all of this, the masked Opacity filter will not affect that, and the masked filters will blend with the color-corrected image. You really need to visualize the Mask: Apply as an internal compositing of the clip with itself, or perhaps it would be nice if Filters displayed them indented like:
- White Balance
- Mask: Simple Shape
- Opacity
- LUT (3D)
- Mask: Apply