I tried using particles to subtract -cut holes- in a mask to expose the underlying layer. It works but the 'hole' represented by the particle moves with the particle. What I was thinking is if it might be possible to make the particle subtract from the mask as it moves and retain the path it has 'cut'
Here is a mockup (using copyrighted material again, sorry LM
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I was thinking this might be useful to create effects that gradually exposed or ate away layers to expose new. Example a particle effect could eat away a wall, or face, or shoot holes in a structure to expose the underlying layer as particles are added to the mask. I'm guessing the same can be done to say draw a scene and add a hidden covering of snow and have it gradually exposed. Lots of possibilities.
Hope the idea is clear.