 On 15 August 2018, the Ducks re-signed Kaše to a three-year, $7.8 million contract extension worth $2.6 million annually.He played in 30 games for the Ducks, recording 20 points, before requiring season-ending surgery after an injury in a game against the Minnesota Wild.On 21 February 2020, Kaše was traded to the Boston Bruins in exchange for David Backes, Axel Andersson and a 2020 first-round pick.