In a world where teleportation magic doesn’t exist, the opportunity to travel a few days journey in moments is beyond value. With only a simple toll, you can be practically on the doorstep of Nizul-tibi before you know it.
Real World: some Indians in the Amazon treat their eyes with a traditional potion applied with palm leaves. Brutally painful, the drug alters vision, giving the jungle's dense green walls greater texture and dimension. You could adapt this to desert or swamps, or other hard to navigate regions.