Armin dropped off of Temeraire's back, watching in confusion and curiosity as he tested the barrier. The mud and dirt slid off the invisible wall like water off a duck's back. In a somewhat inadvisable act, he also let off his cables at the wall, and they were just as ineffective. They didn't even pierce and stick like they were supposed to, but bounced off and clattered uselessly to the ground.

"Well," Armin mused out loud, reeling his cables back in, "I think we are going to need a magician to puzzle this one out. Or maybe a very large cannon..."