The BigShot EFX is a true-bypass effects loop switcher that allows you to set up two separate effects loops and insert them into your pedal chain.
While you're using the EFX loop-A, you can turn a series of pedals on and off with the EFX loop-B to prepare for your next sound effect without affecting what you're doing. Then, with a press of the foot, a whole chain of pedals can be activated!