In the words of Dreadbox:

By combining two exquisite Sinevibes Algorithms, Dreadbox team took this even further by extending the code and making them suitable for use as an effect pedal. Dreadbox favors open architecture in most of their devices, so instead of having several switched algorithms, DARKNESS has a single versatile and flexible formula, that can create from Small and Smooth Reflections up to Huge Shimmering and Endless Reverbs.