Arthur's arrow missed, but the thing suddenly ran into some sort of wall and vanished. Arthur blinked, showered with coins. He looked around for the cause of... whatever that was. Still on his back, he craned his head back and saw in the bushes behind him... Merlin.
"Merlin?! Find a nice hiding spot? You sodding coward, get out of those bushes! This is a battle, not a game of hide-and-seek!" Arthur scrambled to his feet, putting his crossbow back in its back holster. He glanced up again at the spot where the monster had disappeared, but what was the point in asking Merlin about that? Obviously he wouldn't know what mysterious force could have caused that.