Scoria is a planet in the Koprulu sector.
The Terran Dominion built a mining facility into the cliffs. Abathur subjected thousands of banelings to lava, using the extreme conditions to guide their evolution. Over many lava surges, the hunter strain emerged. The successful specimens leapt up cliffs and scattered.
Sarah Kerrigan collected the survivors, which proceeded to ambush Dominion marines that detected their movement. The front entrance of the mining camp was heavily fortified, so the hunters traveled overland, dropped in from the back and destroyed the command center.