The head of Fire wasn't getting rid of Zach on its own, and since Zach was glaring at the head of Poison while beating the snot out of the head of Fire, the head of Poison took it upon themselves to help out their fellow head.
Zach wasn't sure how the different heads and their powers worked, but the two heads he was the least afraid of, even when working together, were the heads of Fire and Poison. So, even when the head of Poison showered him in a slew of smoky poison, Zach didn't flinch, and his attacks continued uninterrupted. He could almost see the gleaming white of the skull beneath.
Yan and the others could only watch without understanding. How was it possible for a human to beat the Hydra? It didn't make sense.
They had barely managed to keep up with the Hydra's regeneration by emptying the Palace's explosives. But Zach wasn't just keeping the Hydra busy or simply occupied. He looked like he was going to smash one of its heads in. And that was just Zach.
