The Growing Shadow

The Growing Shadow is the second mission of Legacy of the Void.

Background
After the revelation that the hybrid were in control of the feral zerg on Aiur, Artanis sought Zeratul's council. Zeratul informed him that Amon has returned, but that the Keystone could be their salvation by showing them the way to the remaining xel'naga. Zeratul told Artanis that the Keystone is on Korhal, and Artanis tasked him with retrieving it while Artanis marshals his forces for the coming war.

The Mission
Zeratul and went to the Void Seeker, but found it destroyed. He is ambushed by Zerg, and he orders his forces to retreat to the nearby nexus. As he reactivated the base, Selendis informed Zeratul that she could no longer sense Artanis in the Khala, an impossibility for all Khalai. She sends Zeratul her Phasesmith, Karax, and tasks them with finding Artanis.

Zeratul's forces fought their way through Zerg hives, and eventually encounters crazed Templar warriors who attack him on sight, Zeratul stating they must have been corrupted by the hybrid. He finds that the Templar base had fallen to the corruption, and attempts to contact Selendis, but gets no response.

He finds Artanis, who is fighting a great rage within the Kalah. Amon's voice then taunts them, stating he comes to offer salvation in oblivion. He takes control of Zeratul's Khalai forces through the Kalah, but is unable to corrupt Zeratul or any of his Nerazim. Zeratul fights his way to Artanis, who has been fully possessed by Amon. Zeratul states that he must sever his nerve chord and remove him from the Kalah and Amon's influence.

Aftermath
""The Keystone... will guide you... to the xel'naga."

- Zeratul's last words

Zeratul and Artanis battle, Artanis wielding red psi-blades and using void energies to repel Zeratul. In the final blow, Zeratul cuts Artanis's nerve chord, but Artanis delivers a fatal blow to Zeratul. In his last moments Zeratul tells Artanis the keystone will guide him to the Xel'naga. Artanis expresses grief that he slew his own friend, and takes his warp blade, intending to carry on his quest to awaken the xel'naga.

Walkthrough
The first section of the mission requires the player to guide three stalkers to a base. This portion introduces the concept of blink, and encounters are limited to small packs of zerglings and mutalisks.

After the base is reached, the player is taught the basics of unit production and economy. A basic balance of zealots and stalkers can clear the way to the Templar base. Two zerg bases are in the way and will occasionally send moderate sized attacks to the protoss base. Mineral pickups are scattered through the map, and are helpful for bringing an army up to speed quickly. In addition, void pylons on the map give the player handfuls of stalkers.

After the Templar base is cleared, there is a section where the player controls Zeratul and four stalkers must fight their way to Artanis. As Zeratul is permanently cloaked the the enemy does not have detection, this section is impossible to unintentionally fail.