Complex sentence: Death's Head is hired by Mys-Tech to retrieve Killpower; while the two fought, Motormouth and Tuck, Death's Head partner, went on a shopping spree on an alien planet.
Split into simpler sentences: Death's Head is hired by Mys-Tech to retrieve Killpower. While the two fought, Motormouth and Tuck (Death's Head partner) went on a shopping spree on an alien planet.