Swarm Host

The swarm host, called the "egg monster" by terrans, was a zerg siege strain that emerged within Kerrigan's Swarm during the events of the Second Great War. Generated by an infestation pit, it burrowed into the ground and produced a seemingly endless supply of short-lived locusts from a breeding organ on its back, allowing a single swarm host to wear down and overwhelm an entire army. It was adapted by the evolution master Abathur from the primal hosts of the world Zerus.

Biology and the locust incubator#

The swarm host carried a large, mushroom-shaped structure on its back that served as a living breeding ground. This incubator weaponized the millions of diminutive larvae that inhabited the creature's acidic bloodstream. Through a simple system of membranes for matter exchange, glands that flooded the offspring with hormones to hyper-accelerate their growth, and ducts that carried them efficiently to bubbling pockets on the incubator's surface, the swarm host birthed deadly but short-lived locusts to destroy any threat to the Swarm. The same larvae also fed on the host's damaged tissue, sealing wounds and destroying any foreign matter that entered its body. When the creature was threatened or drawn into combat, a subtle chemical reaction signaled the larvae to head for the incubator, where they were matured into living weapons.

To deploy, the swarm host buried itself in the ground. Its legs bore powerful muscles that could vibrate at hypersonic speeds, in a manner not unlike the teeth of the nydus worm. Even so, the creature could not at first burrow quickly enough to keep pace with shifting battle. To correct this, a set of fragile but regenerating capillaries was added: when the swarm host dug, these capillaries broke and its acidic blood softened the soil, letting it sink underground in seconds. A specialized skeletal system of flexible osseous structures, which slid and locked into position much like the hydraulics of a terran siege tank, let the swarm host hold its position and balance while spewing locusts or enduring heavy fire. The strain's great limitation was its lack of mobility, which left it exposed to faster enemies wielding area damage.

The swarm hosts of the Leviathan Brood were uniquely specialized for amphibious assault and carried genetic advantages that let them move swiftly through oceans to fall upon prey from the water.

Origin and history#

The progenitors of the swarm host were a strain of primal zerg called primal hosts, native to the world Zerus. The Swarm first encountered them when they were used by the primal zerg against Sarah Kerrigan's forces under the pack leader Brakk, though one large and powerful primal host named Slivan was herself a pack leader. The evolution master Abathur incorporated the strain into Kerrigan's Swarm soon afterward, adapting the primal host's essence to create the swarm host proper.

Later, as primal zerg fought alongside the Swarm, many swarm host strains began to merge again with their primal host progenitors, producing hybrids that shared traits of both. Reports within the Terran Dominion suggested that swarm hosts eventually developed the ability to spawn locusts even without being burrowed. Swarm hosts enslaved by the Cerberus Program were enhanced with microfactories that let their handlers control the spawned locusts through remote-controlled headgear.

During the End War, a number of swarm hosts came under the control of the fallen xel'naga Amon and were inducted into his brood. They were destroyed on Aiur by the Tal'darim Highlord Alarak and the Nerazim Matriarch Vorazun.