(And sometimes you go, whoopsie! that didn't work!, put it away, come back later and look at it with fresh eyes, say, hey, that's actually not a bad effect...)
What I find interesting is that I assumed the intense borders were an afterthought to clean up edges or hide a bit that didn't work, but the process image clearly shows that's not the case. So extra bravo, as that really visually sproiks the intensity of the horror.