Swamped

You try giving the desert horse a light poke on its right with your mudpike. It responds by turning left.

"Okay, it probably figures there's something to the right, so it turns," you muse. "Now, if only we could go a bit faster..."

You hear a loud slap, and then feel your mount pick up speed. You turn around to glance at Rivers.

"What?" she asks. "I just gave it a good whack on the backside. Figured it was worth a shot."

"Well, I guess it was," you say. Then you notice that the Wanderers are running in the opposite direction from you.

Naturally, this raises the question: what, exactly, are you heading towards?

You turn around, looking for signs of an emerging tunneler up ahead. But you don't see anything. Just the wagon, and Rider, and a few panicking animals running away...

This is worrying. On the other hand, you find it hard to believe that Rider wouldn't take notice of the animals. He can be reckless about his own well-being, sure, but if he thought there was a real problem, he'd warn you and the wagon.

Suddenly, you hear a loud bellow somewhere behind you.

"Tunneler!" Rivers shouts. "Looks to be mature. Those guys we were fighting seem to be heading for it, damned if I know why."

The hell. They stop chasing you to pick a fight with a mature tunneler? That doesn't make any sense. And why are the animals running, then?

"Sandstorm!" Rider shouts suddenly.

Oh. Well, that explains the animals at least.

What now?