Are these sentences properly worded?

The mage found Dorn and saved his life by creating metal golem parts to make up the left side of his body. These plates and parts had to be replaced multiple times over the years as Dorn aged and outgrew them, which was an agonizing process. Even after the slaughter of the merchant party, Dorn still had to serve the wizard, to pay him back for the life-saving transplants as well as the years of service that his parents owed.