With each hit, the golden body of the giant hydra liquidated around the wound and would turn into a hardened golden scab that would not regenerate as soon as the Kopia's fire-augmented blade passed through.
Zombie was using the chance he had – the electric charge of Cranberry's attack had already faded leaving only the aftereffect in form of the paralysis status that would fade in a few more seconds.
The difference between the blue undead shredding every single piece of the previous form of the sigil monster was that he thought that the beast had no life signature.
But, well, that wasn't true.
It was just that before, he expected a truly massive life signature and basically dismissed the tiny little light of the actual body of the monster – of course, that the precious shell that it could create did not count as a living being, how could it?