 He made his NHL debut on November 5, starting against, and defeating, the Edmonton Oilers 5–4.He recorded his first NHL shutout several games later on November 22, making 15 saves in a 2–0 win against the Atlanta Thrashers.Mason continued to start games upon Leclaire's return from injury and was named NHL Rookie of the Month for November after posting a 5–2–1 record, including three straight wins and two shutouts.