In StarCraft II: Wings of Liberty, the artifact recovered from Xel’Naga temples is called the Xel’Naga artifact.
The artifact is assembled from several pieces that Raynor’s Raiders recover during the campaign. Tychus Findlay presents the missions as lucrative archaeological jobs funded by the mysterious Moebius Foundation, giving Raynor a reason to pursue the pieces across multiple worlds.
The artifact later becomes central to the campaign’s final conflict. Its power is connected to the Xel’Naga and to the struggle involving Kerrigan, the Zerg, and the greater threat posed by Amon. The artifact therefore begins as a job target but becomes a crucial part of the story’s resolution.
It is distinct from the Psi Emitter, a Terran device used in the original StarCraft, and from the Spear of Adun, a Protoss arkship featured in Legacy of the Void. “Xel’Naga artifact” is the broad canonical name used for the assembled device.