Magi: The Labyrinth of Magic Vol. 8 (manga)

Alibaba's old friend Cassim has fallen to evil and transformed into a Dark Djinn that threatens everyone in Balbadd. The battle rages, and even Sinbad struggles to hold his ground as he fights alongside Alibaba against Cassim and Judar. And on the sidelines, even more enemies wait for their chance to pounce. Without Aladdin and Ugo, the forces of darkness seem to have the upper hand...