Zecora, as part of her torture, has been tossed into a hole and left to rot. Fairly literally, because her injuries have been left utterly untreated and are rather fiercely infected at this point, but the real harm has been isolation and sensory deprivation.

So challenge one? Finding her. The catacombs are mazelike and hold denizens that should not be released, so injudicious choices will only bring disaster on the rescue party. Challenge two is Zecora herself: the moment she's freed of her iron bonds, she will make a panicked retreat into a completely incorporeal form to escape the pain. How do you rescue someone insubstantial?

On the upside, she's not going to fight you.