This unit is the post unit of the Swarm.The unit has very efficient abilities especially against Terrans.The first ability is called the plague which makes the affected zone visible and energy consumer place.The time of the plague effect is nearly 50 seconds which is enough to burn the buildings.If the applied zone is Terrans the building can loss the energy into the critical range which means there must be repair if you do not repair the building will be lost.The second ability is the Dark Swarm Ability which deactivates the enemy range units under the abilities location.This ability can be used against improved Protoss armies with  light attack units like Zerglings.The third ability is the consume ability which will converts the friendly units energy into mana energy which will be very useful for usage of Defilers.