The Destroyer squads were the pariahs of the Legiones Astartes, specialist units wielding weapons so abhorrent that their use stained the honour of any Legion that fielded them. Armed with rad-weapons, phosphex, and chem-munitions, they waged a form of war that poisoned worlds and left nothing but ruin in their wake.
To serve as a Destroyer was to embrace dishonour, for their arsenals violated the ideals of the Great Crusade and marked their bearers as outcasts even among their own kin. Yet every Legion maintained such squads for the wars too foul to fight by any other means, unleashing them upon foes deemed beyond redemption.
Among the World Eaters and the Death Guard, the Destroyers found a grim kinship with warriors already inured to atrocity. When the Heresy came, these weapon-bearers needed little tempting, their souls long since surrendered to the calculus of annihilation.