The Joker walked toward the melee, which he could see through the mountains of boxes. Good. Alright, so this was working out.
He pulled a small, black, pear-shaped object out of his pocket and threw it over the crates. He waited until he heard the pinging sound of the metal sphere hitting the floor.
It bounced twice and then rolled to a stop. It was a grenade, with a smiley face painted on the front. It also ticked merrily away before buzzing to indicate it was done playing around.
The grenade wasn't too powerful, but the point here wasn't to blow the bats away. The blast went off, rocking a pile of crates which then tumbled to the ground one after another. Several hit The Joker's henchmen, crushing them instantly. Wood splintered and cracked for what seemed like hours. When the dust settled, things were eerily quiet.
The Joker stepped out from behind his hiding spot, taking stock of how many had survived the falling boxes. He waved merrily with the semi-automatic in the general direction of the Bats. "Hi," he said cheerfully. He stood, his head keened slightly to the side, his shoulders hunched. He was still grinning, still deathly pleased they'd shown up so promptly.
He held the gun out, his aim swinging from one bat to another. "Bats, bats, bats everywhere. I have an infestation! Ought to call the exterminator. Oh, wait. That's my job."
He glanced up a Batman, peering through the shadows at him. "What, you suddenly decide I'm too tough for one Bat? Don't mind my blush."