The Abysmal Knight was the most powerful Demi-Human monster who happened to be inhabiting in Glast Heim , serving Dark Lord . He was also powerful as he said to have taken down numerous adventurers in the past . He was once responsible for "killing" Keough when he , Iruga , Roan and Yufa were investigating Glast Heim in the past .
The Abysmal Knight was a dark knight who was seen riding on his black-colored horse with a single horn on its head . He was wearing a nightmarish helmet , a gray cape and the dark armors that fitted on his body .
The Abysmal Knight was a fearsome monster as he was said to be roaming around Glast Heim , taking down on those who dared to venture into this place . In addition , the blade of his sword which was called "Blade Lost in Darkness" can caused even the purest person to turned evil when he or she was stabbed , just of what it did to Keough .
He once appeared in several flashbacks where he first appeared . When Roan , Yufa , Keough and Iruga were investigating Glast Heim , he immediatelly attacked them . Just when he was about to strike both Roan and Yufa , both Keough and Iruga intervened in time and attacked him . However , he eventually slew Keough as Yufa watched in horror , thus traumatising her due to the incident . However , he was later responsible of turning Keough into evil thanks to his sword .
He later appeared in the final battle in Glast Heim . In order to avenge his friend , Iruga engaged him in a fight . Eventually , the Abysmal Knight was destroyed when Iruga , Maya and Judia weakened him with all their powers before he met his demise as he was destroyed by Roan's Holy Cross .