DeathStroke

Deathstroke appears as a boss in Batman Arkham City Lockdown even though he does not appear in Batman Arkham City. He opperates in the Steel Mill. Even though thats were the joker and harley quinn opperate for part of Batman Arkham City.

Biogrophy
Deathstroke appeared as he shot the inmate, possibly as bait for Batman. Deathstroke is talking to Hugo Strange and let him know that Batman was there. Deathstroke began running and then battled Batman. By the end of the battle, Deathstroke was beaten. Batman told Deathstroke that he is finished, and proceeds to kick the gun as soon as Deathstroke tries to get it. Deathstroke was arrested to complete his humiliation.