Why destroy Shakuras instead of cleansing it again?

The temple had saved Shakuras before. During the Brood War, the protoss activated it with the Uraj and Khalis crystals and cleansed the zerg from the planet's surface. Shakuras survived. Why, then, does its next great defense end with the protoss destroying the world themselves?

Vorazun chooses to deny Amon the planet after evacuating her people. Artanis then turns that withdrawal into a trap, drawing more of Amon's forces into the destruction. The old cleansing is a real precedent, but the campaign does not establish that every possible alternative has become technically impossible.

Shakuras on the campaign mission screen. Game © Blizzard Entertainment. Unmodified frame: 옷게 / 옷장 속 게이머. Korean campaign interface. Image source ↗

The earlier cleansing is the right comparison

Blizzard's history of Shakuras explicitly describes the Uraj and Khalis activating the Xel'naga temple against the zerg. It also records the subsequent rebuilding of Talematros. The temple's power did not inherently require sacrificing the planet.

In the later campaign, the protoss prepare a different operation. The recorded briefing describes overloading the temple to drive energy into the planetary core. Once the charge is sufficient, the world will break apart. This is deliberate destruction, not an ordinary cleansing that accidentally goes too far.

At roughly 1:38 in the same recording, Artanis says that configuring the temple without the Uraj and Khalis will take time. The campaign also requires destroying three stones that regulate its energy before it can be overloaded.

The preparation takes time without the crystals; the line does not rule on every alternative. Korean game screen © Blizzard Entertainment. Screen: 옷게 / 옷장 속 게이머, unchanged. Post license CC BY-NC-ND 4.0 linked below. Image source ↗

The missing crystals matter. But that line concerns the preparations being made; it is not a complete account of every way the temple could ever be used. “They had no Uraj and Khalis” is supported. “The game proves another cleansing was impossible under all circumstances” goes further than the scene does.

Vorazun has already decided what she will save

Before the final defense, there is a rescue operation. The protoss reclaim infested launch bays in Talematros so the remaining civilians can leave. Its closing campaign screens show the evacuation being completed. Destroying Shakuras is therefore not presented as a plan to sacrifice its inhabitants along with their home.

Vorazun's conversation after the evacuation supplies the reason for abandoning the world. She considers its infestation beyond recovery and refuses to let it become Amon's domain. Artanis initially objects. The proposal comes from the leader whose people made Shakuras their home, and she insists that their survival does not depend on the planet surviving with them.

Vorazun distinguishes losing the planet from losing her people. Korean game screen © Blizzard Entertainment. Screen: 옷게 / 옷장 속 게이머, unchanged. Post license CC BY-NC-ND 4.0 linked below. Image source ↗

Artanis accepts Vorazun's decision. The exchange gives her a voice in the loss of her own home, and gives his eventual agreement a weight that a simple order to retreat would not carry.

Why stay and fight after choosing to leave?

Artanis adds the offensive part of the plan. At about 0:52 in the briefing, he proposes luring more of Amon's zerg and hybrid through the gateway. They will overload the temple and escape after enough enemies have arrived to make the loss hurt.

Vorazun immediately raises the cost of committing their own forces. His response is to take responsibility for the defense. The resulting battle has two connected purposes: hold the temple while it is prepared, and make Amon pay for the world he is overrunning. It is not an attempt to reclaim the city for permanent resettlement.

The destruction thus answers a strategic and a personal question at once. Amon loses the prize and the forces drawn onto it; the Nerazim leave with the people who can carry their culture forward. In a later conversation, Vorazun speaks of their traditions enduring after Shakuras is gone.

There is room to question whether this was the best possible choice. The campaign's answer to why they made it is narrower and clearer: evacuation had become abandonment, Vorazun would not surrender her home to Amon, and Artanis made that loss into a weapon. For another side of what survival costs the protoss, see why they sever their nerve cords.