in the new Axe Fx3 firmware there's a very cool option ... in many effects (delay, reverbs etc ...). It is possible to freeze the sound... ok, nothing innovative but wait! ...unlike the "hold" function of other gear there's something new here! With this so called "stack" you can freeze the reverb but by keeping to play the same reverb is present both "in loop" in the background, and on what new you are playing. This allows you to get very cool soundscapes, drones, or complex rhythmics with delays... In this video I just having fun testing this "stack" option. I've setted the on / off of the stack on a footswitch in old mode, every time I re-press and hold the footswitch it switches on or off the reverb loop; obviously you can also adjust the attack and release speed of the effect).