Hammer and Anvil is the second novel in the Sisters of Battle (Novel Series) by James Swallow.
The Sisters of Battle are the Emperor’s most devout worshippers, fierce warriors preaching the purity of the Imperium and scourging their enemies with bolter and flamer. On a distant world, the Ecclesiarchy outpost of Sanctuary 101, was wiped out by an implacable foe - the fearless, soulless necrons. Now, a mission of the Sisterhood has returned to reconsecrate the site - but the metallic nightmares still lurk in the darkness, guarding a secret that has lain dormant for millennia. A vicious battle will be fought - one that can only end in the total destruction of the unrelenting xenos, or the annihilation of the proud Sororitas.