dragon's teeth in an oval across the middle of the battlefield.
that turn out to be the actual teeth of an actual dragon underground. it is a giant mole-dragon that relies on many small limbs all over its body to adhere itself to the top and sides of the tunnels it digs, otherwise its torso would be too heavy to move. it has an extendable neck, strongly acidic drool and the breath-attack "cone of tentacles".