Adjustment layer for all effects

[Shahzad31221637n85z]

There should be an adjustment layer in which we can add effects like gaussian blur or noise and it would effect all the layers below it. This adjustment layer shouldn't be created with brush but also with ellipse or rectangle tool

[davescm]

You can achieve that by putting the layers in a smart object and applying the filter effect to that smart object. That way, all remains editable and you can mask it to whatever shape you choose.

Dave

[Jumpenjax]

Dave knows his stuff! His answer is spot on. I hope he helped you.