Here's a Zerg concept inspired from a leech design. Keep in mind these unit concepts are more for my portfolio, so don't take them too seriously. I thought a good role for this unit would be to damage enemy macro. It would be the fastest burrowing and tunneler unit of the Swarm (maybe also being able to tunnel up cliffs). With no cost of energy it would be able to suck out minerals from Nexi, Command Centers or Hatcheries, Layers, etc. and drain the enemies' mineral stockpile while you gain the same amount in return. At a cost of energy, it would also be able to shut down pylon power temporarily. Also having an energy ability to infest Terran barracks, and be able to create free infested terrans that spawn every few seconds from those barracks for a limited time. And lastly, it would be able to eat a single larva or egg at enemy Zerg bases for a cost of energy as well.