Instrument Racks allow you to layer multiple synthesizers or samplers on a single track.
Sidechain-less Ducking (envelope follower) ableton patcher
The real power of an Ableton rack lies in its 8 (or up to 16 in Live 11+) Macros . You can map dozens of parameters from different internal devices to a single knob for simplified, expressive control. Instrument Racks allow you to layer multiple synthesizers