You create an area of shadow (as the Darkness spell) that is filled with bats (As Bat Swarm) except the swarm fills every area occupied by the darkness. The swarm is stationary. You are immune to the attacks of your own Hungry Darkness but you are still subject to the effects of illumination. It remains as long as you concentrate on it, plus two rounds afterward. If the swarm is destroyed, the darkness is dispelled.