Comb Filter Snapin

Comb Filter "Snapin" (plugin for Kilohearts software AU, VST AAX Re Compatible)

The Comb Filter will mix the signal with a delayed version of itself, creating a filter with repeated troughs and peaks across the spectrum.

It's also possible to process left and right differently in a way that not only gives a wide stereo effect, but also collapses right back to the original signal when mixed to mono.