Enigma.

Enigma combines comb filtering, modulation, filtered feedback, time delay and a reverb-like processor into one effect that maps onto no conventional category. The feedback path is filtered, which is where the stranger results come from, among them barber-pole rises, resonant reverbs, bell and chime tones, alien voices and dub echoes. Modulation offers several waveforms with host sync and play or stop control. Automating the interactive controls is how it becomes something that keeps evolving.