Astrid III is a planet in the Koprulu sector.
Sarah Kerrigan took control of the hive cluster. Abathur then incorporated the feral zerg's adaptation into the Swarm, and created the swarmling strain as a Dominion force was inbound on the hive cluster. Kerrigan very quickly spawned a massive army of swarmlings which she used to eliminate the attackers. She then had the swarmlings destroy the Dominion base.