Purification (mission)

Purification is a mission in the campaign of Legacy of the Void, and the third mission in the Purifier storyline.

Background
With the stasis shield deactivated on the surface of Endion, Artanis and Fenix moved Daelaam forces to the surface of the orbiting Cybros platform. Their goal was to reactivate the ancient Purifiers still in stasis. However, Amon's zerg swiftly took positions on the platform, and were now being reinforced by hybrid.

Mission
""Brothers, you were created to protect the empire, yet we did not treat you as you deserved, as true Templar. I implore you to forgive our ancestor's mistakes, to take up your ancient charge once more, and join us as equals."

- Artanis

The Daelaam took positions next to the purifier core powering Cybros, as the zerg and hybrid attempted to overrun them. Karax noted that the platform was divided into quadrants, and destroying the null circuits on each would reactivate the purifiers on each section. Along the way the encountered a rouge purifier warden that had activated on its own, but its AI had gone rampant.

Upon activating the first quadrant, a purifier modeled after Executor Clolarion addressed Artanis. Artanis implored him to forgive the sins of the past and help him in the war against Amon. Clolarion was skeptical, but said he would discuss that after Cybros had been cleansed of the zerg.

The three other quadrants were cleared, each section activating another wave of purifiers that tore through the zerg hive clusters entrenched on the platform. As the last of the purifiers were activated, Karax was locked out of control of the core, and it powered up. Clolarion fired Cybros's purification beam on Endion, purging the surface of Amon's Brood and all other life.

Aftermath
""The Conclave feared your kind, but they are no more. I know you are true Templar. I have seen it. I ask that we stand as one, or none of us will stand at all."

- Artanis

Artanis contacted the purifiers through Fenix, who linked with Clolarion. He asked the purifier to join them once again in the war against Amon, to which Clolarion stated they were no better than the Conclave who tried to control them. Artanis insisted that they join as equals or else be annihilated, and Clolarion consoled with the other purifier personalities. They agreed to follow, as long as Fenix was allowed to speak for them and Artanis held to his word. The purifiers were now one with the Daelaam.

Walkthrough
The player starts in the center of the map, next to the purifier power core. The mission is to destroy the scattered null circuits while defending the core. While the zerg will attack directly from the southern approaches, defenses should also be made on the northeast approach, as ranged and flying attackers can hit the core from the high ground. A grid of photon cannons with one or two khaydarin monoliths should provide a good defense.

Sufficient number of colossi are valuable in this mission, as they can outrange the static defenses and destroy most of the light units defending the null circuits. Anti-armor such as stalkers or immortals/annihilators should be used to destroy hybrid and ultralisks.

The purifier warden is to the north of the first group of null circuits, and has a similar attack to a colossus with several support drones that heal it. Destroy the support drones, then focus the warden. Wait until a sufficiently large army is ready before attacking it, as while it is not hard to destroy it should be done quickly in case forces are needed to defend the core