Shortly after Kerrigan defeated the United Earth Directorate forces on Korhal and retreated to Tarsonis, the UED responded with a counterattack, sending a pair of Slave Broods to attack Kerrigan's forces.
The UED used scientists to coordinate their zerg forces. Security Guards were assigned to protect the engineers. However, Kerrigan's forces defeated them, destroying the Slave Brood forces and killing all the scientists.
Increases speed and rate of fire for a short time.