"I’m happy to announce that lastly, we have learned the details on the most terrifying of all Zerg forces: the Brood Lord. A true monster of the sky, the Brood Lord can unleash utter devastation upon any foes on the ground."
Brood lords are massive manta-like flying creatures that serve the Swarm's aerial siege units and used only in the largest conflicts. The brood lord releases biological symbiotes on ground targets. These small creatures regulate some of the brood lord’s biological functions, and can also serve as living ammunition. The brood lord has clusters of broodlings squirming under its carapace at any given time. In combat, the brood lord supercharges the broodlings’ aggression and metabolism, turning them into short-lived—but very effective—air-to-ground weapons that tear through personal armor and vehicular plating with ease. However, brood lords themselves are not very durable, and are vulnerable against aerial-strike combatants.
The brood lord was originally morphed from the corruptor. The glowing bulbs on the brood lord’s back are an evolution of the cancerous growths in the corruptor’s tentacles. Alterations at the genetic level turned the growths into sacs capable of rapidly spawning large batches of broodlings. Its tail is also derived from the corruptor, namely its statocyst. The brood lord’s tail structure (including the spikes) constitutes a large biological gyroscope that maintains the creature’s level and orientation. The tail is directly linked to the brood lord's sensory organs, increasing its capability to locate prey. Bone spikes located on the frontal section of the brood lord's wings house an advanced glandular system capable of emitting and receiving high-frequency electrical pulses. With each pulse, a massive spherical field radiates from the creature, coating its surroundings and targets in bio-electric energy. Afterwards, the brood lord's acute receptor glands pick up and process the gathered data. During deep space flights, the glands mutate to detect sources of radiation, electromagnetism, and light.
Brood lords are also capable of adapting their biology to suit their theater of combat. During the invasion of a planet with exceptionally large seas, brood lords evolved to be more suited in aquatic combat, allowing them to chase their prey deep into the planet's trenches.
Brood lords replace guardians as the zerg aerial bomber. Like the guardian, it has a long-ranged ground attack and no defense against air units. Brood lords launch broodlings; the broodlings do damage upon impact, and then act as separate timed-lifespan ground units. Brood lords can sustain a stream of single broodlings; the first attack after a break launches two broodlings. Unless the enemy uses extensive micro-management or air-to-air fighters, the broodlings are an excellent distraction for ground-to-air units on top of the damage boost. Left unchecked a relatively small group of Brood Lords can end up doing catastrophic damage to an enemy base since very few enemy units or turrets will end up actually firing on them.
The combat role of the brood lord fluctuated for a very long time. Many variations of the guardian were presented but the intention was always clear that the development team wanted more out of this new flyer. Finally out of the blue, Samwise Didier concepted the brood lord like a bolt of lightning and thus the design team created the 3D art in accordance to his concept. The head design was lifted from the scrapped morphalisk.
The brood lord's frenzied ability was added in the context of swarm host matches, coupled with mass spore crawlers. As swarm hosts were altered in Legacy of the Void to be more mobile, the ability was deemed unncessary.