*verb is an audio effect working like a standard reverb with some extra parameter modulation possibilities.
Additional to the standard parameter settings some new features are: A longer delay time to attain almost endless reverberation tails, like a freeze effect.
Deactivation of the chorus section to obtain some clean and rather "cold" sounding reverberation.
Modulation of different chorus parameters ('flutter' and 'flux') which results in some experimental noisy sounds, messing up the reverberation.
Furthermore the reverberated signal of the 'verb' effect can be faded in. An additional midi effect entitled *ctrl_verb controls the fade-in/envelope settings of the course of the wet (reverberated) signal.
Further documentation can be found in the Max for Live device if Ableton Live´s Help View is turned on.
credits: The core concept is taken from the [yafr 2]-macro by Randy Jones (credited as a plate reverb in the style of Griesinger) which is part of the Max/MSP library.