Mantic has this interesting loop/splitter box called the Pendulum. You can midi control it, or have it fade based on an envelope.
Pendulum
Its many uses include but are not limited to:
-Auxillary Effects Gate: your playing dynamics control when an effect is present or absent
-Volume swell
-Add a clean blend to any effect or effects chain
-Fade in/out any effect or effects chain (pseudo tails)
-Gradually shift between instruments, amplifiers, or effects chains
-Unique panning tremolos
-Side Chainer
There are 4 modes on the Pendulum, each differing in how the envelope is triggered:
-Blue Mode: Footswitch (momentary or latching)
-Green Mode: Gate threshold, dynamic actuator, sidechainer
-Yellow Mode: Recurring/cyclical, quasi tremolo
-Red Mode: Tapped pattern