Quackulatory filter boost, most commonly associated with the big man Zappa. Get that wicked warped tone, whether it be uniquely aggressive boosting, cocked wah or more subtle lead EQ.
An addition on this model is the option to disengage the buffered bypass with a switch near the output jack. Particularly useful for tone fanatics who have their chain all figured out and need to slot the Energizer in without disrupting things. So if the buffer output doesn't quite play nice with the pedal after it then flick the switch and you're in true bypass mode.