Silica-virae
Silica-virae were ancient monstrous weapons, that scoured away nanites and were later used heavily by the First Legion during the Great Crusade.[1]
They were pronounced as the ultimate heresy by the adepts of Mars and none but the Dark Angels were able to use the Silica-virae. However unleashing such weapons served only one purpose: the utter destruction of life on a world.[1]
Source
- 1: The Horus Heresy Book Nine - Crusade, pg. 110