Using Lu's ability, Cane could sense the second pillar in the rear line of alpha Dex's warrior. That was when he saw Zeke.
Rather than Dexter, Zeke was way more dangerous. He was literally Decratic's right hand man and for him to actually show up here, could be mean that Decratic was nearby.
Cane could feel this was a trick, or at least he was a bait, but then if he tried to lure him toward Decratic, it was not necessary, because that creature was indeed the main target.
The black beast moved forward, faster, while Dexter and Rei were behind him. Black magic was hurled toward the beast, but Cane managed to neutralize it, which surprised Dexter, because he didn't think the black wisp could do such thing.
He must have not yet learned about how Cane neutralized the strong shield around Winter Moon pack. Yes, the alpha couldn't counterattack his magic, but he could avoid it just fine.