Complex sentence: In addition he created a thrash-metal band called Skullzone, along with Johnny Miller and Ryan Duggan, a Chicago artist who owns Hated Skateboards and Drug Factory Press and does much of Maps & Atlases' poster and T-shirt artwork.
Split into simpler sentences: In addition he created a thrash-metal band called Skullzone, along with Johnny Miller and Ryan Duggan. Duggan is a Chicago artist who owns Hated Skateboards and Drug Factory Press and does much of Maps & Atlases poster and t-shirt artwork.