Nessa's Millipede entered a deep sleep and slept through the night. But that didn't stop monsters from trying to attack them.
One of the many benefits of the Underworld's contamination of the forest and the effect it had on the monster was that they were too fearless and hungry to care about the stench of blood and piles of monster corpses to reconsider going after Zach. Their instincts also seemed to be sharper, at least when it came to finding and detecting prey.
The underworld energy had corroded their minds and strained their bodies. It reduced their capacity for rationality and increased their need for food.
It was even easier for Zach to hunt than it was before. He still wasn't sure what to feel about how he was a monster magnet, but he couldn't deny the positive aspects. If he didn't want to be hounded by monsters, he just had to bring Alzara with him. It was a simple fix.