Niadra was created by Sarah Kerrigan when she battled the protoss on Kaldir. Although she succeeded in preventing them from contacting the Golden Armada, one of the protoss ships attempted to flee from the planet and travel to Shakuras. To prevent them from surviving, Kerrigan placed a parasitic larva within the captured protoss colonist Lasarra and dropped the psionic veil that prevented her from being warped back to her people.
After being teleported to the ship, the protoss attempted to warn the Templar but died as the parasitic larva spawned from her body. Shortly afterwards, it began infesting the local animals kept onboard by the protoss and hid within the ventilation shafts where it found a safe location to mature into a queen. Kerrigan gave her the name Niadra and tasked her with eliminating all the protoss onboard the ship. Niadra and her growing brood moved through the ship destroying the protoss, Niadra herself continuing to evolve and grow her powers by consuming the specimens in the ship.
After reaching the bridge and destroying the last protoss on the ship, Niadra and her brood became the only occupants of the craft. She attempted to contact Kerrigan to inform her of this, but her communications were not responded to. With few other options, Niadra decided to continue the Queen of Blades' last directives: to survive, grow her brood, and destroy the protoss, until the day came when her queen needed her again.
As a broodmother, Niadra is a ranged support attacker. She is unsuited to fight enemies alone, and must rely on other units to fight. Niadra is able to quickly breed zerg units to fight for her, and has a regeneration aura that rapidly heals nearby allies. As she continues to consume biomass and evolve, the control she provides and thus the army she can command increases, as does her HP.
Many zerg ground units may burrow, become invisible and may be revealed primarily by detectors, and may not move or attack. Exceptions are the roach, which may move while burrowed, the infestor, which may move and cast Infested Terran, and the baneling, which can detonate while burrowed.
Some units can unburrow via autocast, causing them to emerge and attack when an enemy moves into range.