Hydralisk evolution

Hydralisk evolution' is an evolution mission available in StarCraft II: Heart of the Swarm.

Mission
On the planet Marek V, Ryloth Brood was under attack by Prometheus Company, which has established a heavily fortified defensive line to contain the zerg. Abathur identified impaler colonies nearby, an ancient zerg defensive structure utilized by the Overmind, and suggested gathering their essence to utilize in a new evolution of the hydralisk. A force of hydralisks killed the impaler colonies and used their essence to morph into impalers. The impalers broke the defenses of Prometheus Company and Ryloth Brood descended on their base, destroying them.

Abathur notified Kerrigan of surviving lurker dens. The planet of Cavir was once a birth colony for Daggoth's brood, but was now feral. Lurkers, gone feral after the Brood War, were still alive on the planet. Sarah Kerrigan was able to take control of a number of the lurkers, but lacked the ability to create more. Abathur suggested a key part of the sequence was missing and that a lurker den was required to obtain it. The presence of Kerrigan's swarm enraged other feral zerg on the planet, and she used the lurkers to defend the lurker den until Broodmother Kilysa could arrive to secure its essence.

Gameplay and Walkthrough
In the first part of the mission, the player will command a number of hydralisks against three impaler colonies. Their attacks are telegraphed by crosshairs, allowing the player to micro their hydralisks to avoid damage. When all three impaler colonies are dead, the player can morph their hydralisks to impalers. Upon doing so they receive more impalers and can move to the cliffs to break the Dominion defensive line. After this is done marauders will break the rocks to the east, allowing the player to move their impalers to the main Dominion base and destroy it.

In the second part of the mission, the player receives control of several lurkers. They must advance to the east, stopping to burrow and defend against a wave of feral zerg attackers twice on the way. Once at the den feral zerg will attack first from the south, then the north. Once both waves are dead the mission ends.