David Cain agreed to train a new generation of assassins for Ra's al Ghul. The Demon provided Cain with children to raise as assassins. The training was intense and the few that survived infancy turned on each other. After the young assassins killed each other off, the only one left was Mad Dog. Ra's al Ghul sent one of his Ubu's to dispose of the failure, but the servant took pity on Mad Dog and set him free into the wild. This was unknown to both David Cain and Ra's al Ghul but was discovered by Ra's al Ghul's daughter, Nyssa. Mad Dog's breakdown convinced David Cain that the perfect weapon needed perfect genetics which is the beginning of his project that would lead to the eventual birth of Cassandra Cain.
When Nyssa killed her father and took his place as the Demon, she had Shiva train her new League of Assassins composing of young martial artist including Mad Dog, Circle of Six members, Alpha, and Shrike. When Batgirl sought out Shiva,and was forced to fight with the new League,while Mad Dog sought to kill her. Mad Dog went into a killing spree during which he killed all the League loyal to Cassandra, except for one who Cassandra protected and died for after Mad Dog stabs her, as she knocks him unconscious.