"Maybe I'm just curious," he shrugged, still playing casual, "it's not everyday a league of assassins comes to Gotham."
Maybe the namedropping was cheesy, but it could open doors for some hints. Plus, he was interested in these kids. They didn't seem like the vigilante type, but both were incredibly well-trained and obviously weren't keen on Batman's "no kill" rule. And it was "Batman's city" after all.
"Also you left quite a mess. And you know who thinks he owns this city. And I'm sure you also know who has a thing against lethal force."