A filter that has a lot of dirt and squelch in it.
I was aiming for the old acid type 303 sounds. It's a 2 pole nonlinear B SK filter with extra saturation and resonance. It also has an overdrive section with two 1 pole filters meant to shape what goes into the overdrive. These don't do anything with no overdrive.
There's an example ensemble showing the type of thing you can do with it. There's also an audio example, check it out.