Waylon's atavistic animal genes gave him some resistance to toxins. Ordinary poisons could do nothing to him. But fear toxin affected more than just the body, and Waylon's toxin-resistant constitution could not completely fend off its assault on his mind.
For an instant, Waylon seemed to see the aunt who had abused him as a child, the neighborhood children who had thrown stones at him and called him a monster...
"Damn you! How dare you!"
Scarecrow had never expected his unfailing fear toxin to backfire against Killer Croc, failing to bring the crocodilian monster down under the weight of his terror. He wanted to say something in his defense, but Killer Croc, under the influence of the fear toxin, had no interest in listening.
"Want to see my fear? Take a look at your own first!"
Waylon could still cling to his sanity for the moment, but the frenzy and bestial instincts unleashed by the fear toxin made him want to tear something apart.
Scarecrow and his mercenaries right in front of him made excellent targets...
Only after Waylon had vented some of his anger and heard police sirens did he abruptly come back to his senses. Scarecrow's mercenaries lay sprawled all over the ground. Some had their arms broken by his twisting grip; others had their shoulder armor pierced by his sharp crocodile teeth.
Fortunately, all the tea and cookies he had shared with Little Girl lately had done quite a bit to mellow him out. Even in his panic and rage, he had only broken the mercenaries' arms and legs, not their necks. They looked miserable and bloody, but not one of them had stopped breathing.
The culprit, Scarecrow-Jonathan Crane-had also had an arm broken and been tossed aside. He had passed out from the pain long ago.