As much as I love guitar parts built from fast and hyper-syncopated power-chord figures, some of the heaviest riffs I’ve ever heard are built from single-note patterns alone. Legendary metal bands such as Metallica and Megadeth, as well as relatively newer groups like Children of Bodom, At the Gates and In Flames, have used crushing single-note riffs as the centerpieces of their most powerful songs. In this month’s column, I’d like to focus on how to construct interesting, heavy and deceptively complex single-note riffs.