In C minor, the i–♭VI–♭III–♭VII progression is Cm – A♭ – E♭ – B♭. The minor four-chord loop: dark but driving. Huge in rock, pop and film.
The library above is set to i–♭VI–♭III–♭VII in C minor. Press Play to hear it with strummed guitar, bass and drums in a rock groove, tap any chord to hear it on its own, or pick another key or a capo.