Reverb Sidechain
Set your sidechain compressor up as normal, but this time add a reverb (yes, inserted) BEFORE the compressor. This will create a bigger pump as the compressor will suck both the bass and reverb. Tweak around with the settings, you can get some bad ass unique pumping EFX going with this one. Boom!

Sony’s Oxford Reverb inserted before the sidechain compressor in Reaper