The Patchwork Girl of Oz Chapter 12 - The Giant Porcupine

In which Ojo and his companions encounter a tricky stretch of yellow brick road that moves backward beneath their feet, compelling them to adopt an unusual method of travel by walking backward to advance. They then confront Chiss, a fearsome porcupine-like creature whose quills they cleverly collect to protect future travellers, all the while applying a magical charm to heal a painful wound.