The base is original from the producer (chords and melodies), but is complemented with elements that complement the song that come from samplepacks, usually, vocal chops, guitars, wobbles sections, glitch effects. It is the standard in which most of producers work, in a project you will find MIDI files made by the producer, but also melodic loops.
For melodical elements I've used Nexus, Serum & keys loop. Sections of project are organized with color.
Sample pack NOWARE! Beats - GHOSTS VOL. 1
Loop name #12 [140 bpm] Nightmare - C#min