The tactic that Duncan employed in his hunt for the cannibals was a truly tried and tested tactic used by the hunters.
First, one injured a beast severely, but not mortally, and then put them out in an open field. The cries of the injured beast would attract other predators, who would sense its weakness and rush to kill it. When the predators entered the hunting zone, the hunters will kill it with an arrow or a spear from the distance.
This was an effective method to hunt in the wild. The only problem was coming across powerful beasts that would be able to escape the arrows and spears. Usually, this tactic was not ideal to hunt cautious beasts or beasts that specialized in speed. The moment they sensed something wrong, these beasts would escape without looking back.
However, if this was used to hunt the cannibals, Duncan had confidence that it would work. This way, he didn't need to search for these detestable things. They would deliver themselves to him.