Besides the above works and a commentary against various sects of Monophysites (Severians, Theodosians, Cainites and Acephali) he left eleven discourses in defence of Pope Leo I and the Council of Chalcedon, also a work against the Agnoetae, submitted by him before publication to Pope Gregory I, who after some observations authorized it unchanged.
Damian was very active in fighting views that he considered heretical, including not only tritheism, but also the Chalcedonians, Pope Leo's Tome, Bishop Julian of Halicarnassus, the Agnoetae, the Meletians, the Acephali, the Gaianites (supporters of a rival to Theodosius I), Stephen of Alexandria and Paul of Beth Ukame.