"WORMHOLE" is a delay pedal that can bend delay time by the reflective photosensor. When the repeat knob is full, it starts oscillate. Because it has a limiter circuit in the feedback section, it doesn't make too much loud oscillate sound. You can get kind of vibrato or chorus sound when the time knob is lower position.
A standard 9 volt DC power supply with a negative center 2.1mm barrel, no battery option