In 1986, Dunn left Venom to form the band Mantas which has recorded two full-length albums, Winds of Change in 1988 and Zero Tolerance in 2004.

In 2006, Mantas toured with German hardcore techno act Scooter in Germany as an additional member on guitar;[1] he admitted being apprehensive about the job, as he wasn't a fan of Scooter's music, but admitted to greatly enjoying the tour.

[3] In 2009, he guested on German metalcore band Last One Dying's debut album The Hour of Lead and released the Dryll EP Digital Surgery which was available at live shows only.

In 2010, Dunn and former Venom members Antony "Antton" Lant (drums; brother of Venom frontman Conrad "Cronos" Lant) and Tony "Demolition Man" Dolan (bass, vocals) formed a band, initially called Primevil and then M-pire of Evil.

[citation needed] In May 2018, Dunn underwent emergency heart surgery (double bypass) in Lisbon following a life-threatening incident.