Sean “Diddy” Combs’ ex-assistant Capricorn Clark — who once reportedly dubbed him “the devil’’ — testified against the disgraced hip-hop mogul at his sex-trafficking trial in Manhattan on Tuesday.

Combs, 55, is accused of using his fame, fortune and many businesses to run a racketeering scheme in which he controlled and manipulated ex-girlfriend Cassie for over a decade, using violence and threats, forcing her and others into drug-fueled “freak-off” sex marathons that went on for days.