The movement of the shadows has Oliver's attention. He hasn't seen anything like that since the incident on the island, an incident involving one John Constantine.

A growled curse as Shadow, of all people, goes bounding into the fight like it's playtime. Great. So he's not just a kid, he's an overcharged one. "What are you doing? This isn't a game!" Lives were on the line and it was his job to keep them on the living side of the equation.