Ultralisk

The ultralisk was the most powerful ground strain the zerg Swarm possessed, a massive living battering ram that served as its siegebreaker. Evolved from the docile brontolith, the ultralisk was around 20 meters long and 5 meters tall, armored in an exceptionally thick carapace and armed with bone scythes called kaiser blades. When ultralisks were deployed against terran forces in the Koprulu Sector, Terran Dominion marines were advised to maintain a wide perimeter and call in air support.

Origin and physiology#

Ultralisks evolved from the docile brontolith, a creature the ultralisk came to bear little resemblance to. The brontolith's genetic code was dissected, rebuilt, and repurposed multiple times, each phase eliminating less desirable traits while augmenting the creature's ability to withstand severe punishment, including the brontolith's superb immune system. As a finishing touch, the Swarm added a gene that would replace the creature's organs. The ultralisk's genetic material was subject to countless tests and experiments, and only the final viable code was utilized by the larvae that produced it. By the end of its development the ultralisk stood as a living battering ram roughly 20 meters long and 5 meters tall, fast for its size despite its bulk.

Weapons and defenses#

The ultralisk attacked using large bone-like scythes that protruded from its back, known as kaiser blades. These scythes were nearly indestructible, their density, bevel, and edges honed at the genetic level, and their monomolecular edges could tear through most substances with ease, slicing through armored vehicles and eviscerating entire squads of light infantry in a few swipes. By 2500 at least some ultralisks sported four kaiser blades rather than the usual two, and by the Second Great War four blades had become the standard. The creature's size was itself a weapon, allowing it to charge with enough ferocity to destroy protoss force fields. Ultralisks enslaved by the Cerberus Program were further enhanced with heat-treated titanium blade implants.

The strain's defense rested on an exceptionally thick carapace. Dominion scientists believed the larva's highly resistant carapace had served as the template for the ultralisk's armor; tests showed the diamond-shaped chitinous scales were combined with foreign compounds and organic tissue multiple times, producing very light plates with an unmatched level of hardness. A gene within the ultralisk's code existed for the sole purpose of growing heavily armored copies of the beast's primary organs in random locations across its body, while the brontolith's immune system, improved upon for the strain, let it thrive in the most toxic and inhospitable environments. Its weak spots lay in its head, particularly the mouth and eyes, its underbelly, and around the neck, where the plating was thinner.

Evolution across the wars#

Ultralisks during the First Great War and Brood War were slimmer and more agile than later evolutions, built with durable muscle and sinew rather than heavy armor. By a later point, prolonged exposure to vespene gas had enhanced the strain's physical capabilities, hardening its exoskeletal shell and granting it the ability to carry out anabolic synthesis through altered glands that produced endorphins and adrenal fluids. By the Second Great War the strain received substantial additions to its internal structure, including a complex sensory system, an auxiliary nervous system, and specialized muscle fibers that expanded or contracted in reaction to stimuli, allowing an ultralisk to maintain speed even with its hind legs severed.

When terrans first encountered ultralisks, they observed that the creatures suffered balance issues and were easily toppled by artillery fire or loss of limbs. By the Second Great War, "unstoppable" ultralisks had appeared, sporting more kaiser blades and heavier carapace armor; though terran intelligence revealed the additions to their internal structure, the data offered little toward a counter. During that conflict some ultralisks were combined with the essence of the primal zerg of Zerus, making them truly relentless killing machines, while ultralisks birthed by the Leviathan Brood were terrifying figures of spines and blades.

Study and reconstitution#

Ultralisks were submitted to countless genetic experiments and studied by terrans to a significant extent, with Avernus Station and the Castanar space platform serving as examples. During the final stages of the Second Great War, Sarah Kerrigan was able to reconstitute the ultralisk strain from test subjects held at the Skygeirr Platform laboratory. Research stations on Korhal later allowed her to assimilate the noxious strain of ultralisk and to reconstitute the torrasque strain.