Gathering material
The Wild Bones were unable to see what Zain could do, at least the extent of what he could do, because he had fought the devastating creatures mostly in the subway, and they were distracted trying to fight for their own lives against the zombies that were gathering around them.
Now though, they were able to witness Zain's greatness. He would constantly break parts off of the cars around him with ease, as if they were made of bits of cheap plastic, then as if he had a birds eye view, he was keeping an eye on everyone in the group.
He would use the bits of the vehicles he had torn off to throw them toward the zombies that were attacking them and getting in the way of them fighting the stage 2 Titan. As Zain inched closer, he soon stopped throwing items at them and instead used his two machetes he had on him instead.