The LFO section provides controls for the Low Frequency Oscillator (LFO) used to modulate the Delay time.
The Wave control lets you interpolate between a triangle wave and a sine wave for the modulating LFO.
The L/R Offset control lets you adjust the phase offset for the LFO waveform applied to the left and right channels.
Click the Retrigger button to reset the LFO phase. This lets you manually start the filter sweep from that specific point in time (or using automation, at a specific point in your arrangement). Clicking the Trig button also forces the Mix control up if it is too low while the button is held; this ensures that the sweep is audible.