How do you unlock devil trigger in Devil May Cry 3?

After numerous battles, an encounter with a being calling itself Jester,[18] and another run-in with Lady, Dante attains the tower's summit and battles Vergil. Vergil soundly defeats Dante, steals Dante's amulet, and departs. As a result of his defeat Dante's dormant devil powers emerge, and he sets off in pursuit. After numerous battles, an encounter with a being calling itself Jester,[18] and another run-in with Lady, Dante attains the tower's summit and battles Vergil. Vergil soundly defeats Dante, steals Dante's amulet, and departs. As a result of his defeat Dante's dormant devil powers emerge, and he sets off in pursuit.