The Envelope mode causes the effect to react to your playing level. When Chorus is selected, the wet signal diminshes as you play louder and comes back in at lower playing levels. With the Multi type, the opposite effect happens. The wet signal increases as you play louder, and diminishes at lower playing levels. With Vibrato selected, the speed of the vibrato increases as you play louder, and slows down at lower playing levels.
In Ramp mode, press and hold the bypass footswitch to ramp in the effect. Use the Ramp knob to adjust the speed of the ramping effect. The effect ramps more quickly as you turn the knob clockwise.