From one little larva

They were beautiful in their creation. One larva had all the material and genetic memory of every member of their twisted "RACE".  They were more than a hive they in their truest sense they were one organic creature. It spreads a film over the ground like a celluar membrane.  Their buildings were actually organs of the whole connected through the membrane to the others feeding the larva whatever stimuli is required. The individual moving creatures were connected psionicly.  They could spawn and mutate creatures so fast it the psionic connections would quickly be over powered and crowded if you tried to control all of them at once.  This was the source of his brilliance.  

Instead of directly controlling all of them with his own psionic energy, he built the queen and overlord.  They were units that created a network of control.  Each would psionically control a portion of the population and then each queen would psionically control a portion of the overlords and they would in turn be controlled by the zergtul.  And the zergtul's answered to the overmind and the over mind to Zyr.  Zyr could give over arching directives to the overmind and watch them be fulfilled or he could take direct control of any piece of the network and give direct orders down to the very unit.  It was wonderfully autonomous and able to be preciously tuned. 

Zyr laid the larva on the ground and commanded it to create a hive.  It mutated in moments and began spawning its own larva.  He commanded the larva to transform into drones, simple creatures that could consume the environment around them and bring raw materials to the hive to digest.  An hour later the surround trees and creatures and been consumed and the hive has spawned more larva which mutated into other organs for the hive.  The creep, film of live for this hive, spread and reached out over the darkwood floor.  

Too many creatures were being created, the hive population was into the hundreds within another hour.  So overlords and queens were needed.  Once the structure was in place to support a vast population he mutated one of the larva to a Zertul and linked it to the overmind.  Then he built his forces. 

The simple zergling.  It was an eating and blood thirsty insect.  Laughable as a single creature but they were spawned in the thousands and meant to overwhelm battle lines of much tougher fighters. 

They were supported by Hydralisks. Slythering creaters that were a bit slower but could spit acid at a distance. 

The Multalik had wings and could spit acid as well. 

Roaches were a back bone of the force used to burrow into enemy territoy and with strong shells of armor they could take lots of punishment.  They were best against defense structures of an enemy, their corrusive bile would destroy stone and steel.

Then there was the ultimate fighting machine -- the Ultralisk.  Think armor coverred its body, massive claws and teeth allowed it to quickly destroy anything it wanted.  100 times the size of a man he was confident these could fight dragons. 

Then there was the glory of the zerg in the Corruptor.  They were so great because they could adapt to any situation.  This often required aquiring new dna to use for mutating new creatures.  Or infecting the enemy with zerg eggs to control them directly.  This is was the corruptor did.  Spraying spores it could infect anything organic with the zerg eggs and bring them into the hive is the strength of the overlord allowed it.  It could also consume and process the genetic make up of other organics and mutate larva spawned at the hive to imitate the consumed creature.  This was why the zerg will always win.

Oh and so much more. The zergtul were capable of controlling this hive but he wanted something special.  Something that knew how the creatures on the prime fought and thought.  It would need to be something with psionic abilities in order to work in this network and something with the will to hold their control over the zerg hive.  Yet he would need it to be completely loyal to him.  He knew who he wanted but did not yet know where to find her. 

Zyr looked over the colony that had spawned in less than a day.  Thousands of creatures and miles of hive.  He then took one little larva in his and and with an audible pop arrived on the blood isles well behind his defensive lines and laid the larva on the ground.