 In his last act before being killed by the possessed Artanis, Zeratul severed the Hierarch's nerve cords, cutting him off from the Khala.Artanis rallies what few managed to avoid corruption and flees Aiur on the "Spear of Adun", rallying an army to fight Amon's forces and destroy his power base, before returning to Aiur with the Keystone (the Xel'Naga artifact used to purge Kerrigan of her own corruption).Convincing the possessed Khalai to sever their cords and break away from the Khala, their action sends Amon's essence into the artifact, which then implodes, banishing his essence into the Void.