Layer Hopping Trio

Karenna Stone, V Bowman, and Quodex McCain, a trio of friends, are all tasked with slaying a dragon in the center of the layered world. The task giver is the god of their weird world. Can they locate the one way to bypass a layer of indestructible rock? Can they stop the invaders from the center of the world? Can they survive in the dangerous, wild world? And what of the weird animals that seem to have merged with either plants or mushrooms?