he moved again on loan, this time to Major League Soccer side Colorado Rapids on 20 February 2018 until the end of the 2018 MLS season. On 12 July 2018, it was announced that Mason would end his planned season-long loan early and return to Wolverhampton. As the 2018–19 season began in England, Mason still remained outside of the first team plans at Wolves, who had by now been promoted to the Premier League. On 31 August 2018, he was loaned out to League One Portsmouth until January in a move which saw him again link up with Kenny Jackett who had signed him at Wolves. However, he made just a single appearance in the league for Pompey, appearing as a late substitute against Wycombe Wanderers. On the final day of the January 2019 transfer window, his contract with Wolves was terminated by mutual agreement to allow Mason to find a new permanent club. Milton Keynes Dons On 4 June 2019, Mason joined newly promoted League One club Milton Keynes Dons. Having suffered another injury setback early in the season, Mason's appearances for the club were limited and at the conclusion of the 2019–20 campaign he was one of nine players released. Mason re-joined the club in August 2020 ahead of the 2020–21 season. On 19 January 2021, Mason scored a 28-minute hat-trick in a 3–1 home win over Fleetwood Town. Cavalry FC On 10 May 2021, Mason signed a multi year deal with Canadian Premier League side Cavalry FC. He made his debut for Cavalry on 18 July against the HFX Wanderers. In his third game for Cavalry on 3 August, Mason scored his first goal for the club, netting the first goal in a 2-1 comeback victory over Albertan rivals FC Edmonton. In January 2022, it was announced Mason would return for the 2022 season, his second with the club. After two seasons Mason would be the leading goal scorer for the club. In January 2023, Cavalry announced they had exercised Mason's contract option for the 2023 season. International career Mason was born in Plymouth, but was eligible to represent the Republic of Ireland because his mother was born in County Mayo. He represented the Republic at under-16 and under-18 level before being called up to the under-19 squad for the Four-Nation tournament and their qualifying games in the UEFA Under-19 European Championships. He played in their 2–0