Stylistically STLNDrum is a Lofi producer so real nice pocket with fairly loose drums hip-hop style.. very chill low tempo type stuff..
So he's got this Ableton template for free from/stream of consciousness type set up.. and how he describes it is as an approach for putting down ideas without worrying about tempo so much but more so groove...
So how he sets it up is he puts down a very basic snare kick pattern for 4 or 8 bars then he has that track bussed so it's resampled into another track so it continually loops the snare kick pattern.. then somehow he has another whole series of channels set up with different instruments which is also bussed to the resampled track where the drum loop is free spooling on and on... As he uses other instruments the drum loop is muted on the resampled bus track but somehow you can still hear and monitor snare kick loop... If he has a Rhoades track and starts hitting some keys it then mutes the drum loop on the resampled track BUT you're still able to hear the drum loop for timing.. it looks like he's able to record each instrument on it's on track as well as well as on the resampled track... More or less you'll get a series of free form ideas laid out on the resampled track as well as the separate tracks for each instrument..
I hope that all made sense.. he is using Abletons looper in but not sure how to translate that to Reason or if it's possible.. I've probably didn't describe that correctly lop