Scoria was a volcanic planet occupied by both the Terran Dominion and the Zerg Swarm during the Second Great War. The Dominion used the planet as a mining facility, while the zerg used its extreme climate to drive their evolution.
Abathur repeatedly subjected thousands of banelings to the planet's natural occurring lava tides. While most banelings died, some learned to jump onto higher ground to avoid the lava. Abathur adapted the survivors' traits into the current baneling strain and created the hunter strain.
Kerrigan located and collected the hunter banelings and directed them to attack the Dominion's mining facility, which had been built into the cliffs. The hunter banelings' jumping ability enabled them to go around the base's heavily guarded front entrance, and attack from the rear instead. The banelings destroyed the command center, crippling the facility.