In a way, Yanael and the others were lucky that an underworlder had come to retrieve the artificial life heart from the Basilisk's corpse while the dolls kept Soara distracted. If she had detected him, he would have died, and they wouldn't have had anyone to guide them through the spacious tunnels of the Underworld.
It would have been the same if he didn't come at all.
The tunnels weren't winding or unnecessarily complex like in a maze, but the maids and students didn't know where to go. Eventually, they might be able to map out the place and find something that could help Alzara concoct a potion that would work on even Zach's petrification.
But the Underworld was vast. It could take them weeks or maybe even months before they found anything useful. It wasn't even worth considering since they would not be allowed to roam around freely, and there was no telling how long Zach could last with the petrification trying to swallow him.
