It means 'Shadowhunters: Looking Better in Black Than the Widows of our Enemies Since 1234'.
"Death's got an Invisibility Cloak?" Harry interrupted again. "So he can sneak up on people," said Ron. "Sometimes he gets bored of running at them, flapping his arms and shrieking..."
"Do you remember me telling you we are practicing non-verbal spells, Potter?" "Yes," said Harry stiffly. "Yes, sir." "There's no need to call me "sir" Professor." The words had escaped him before he knew what he was saying."