Legio Mortis

The legion’s core is its Imperator-class Titans: the flagship Dies Irae (of Horus’s 63rd Expeditionary Fleet; it marched from Isstvan III all the way to Terra) and Aquila Ignis, built in the forge-yards of Daedalia Planum, which at the Schism of Mars finished off the last engines of Legio Tempestus in Magma City. At the Siege of Terra Mortis was unleashed at full strength — hundreds of Titans against the Mercury-Exultant kill-zone under Dies Irae; by that hour Chaos had so corrupted many of the god-machines that they regenerated their wounds and acted without a princeps. There Mortis destroyed its ancient enemy, the loyalist Legio Ignatum, and broke through the Palace walls, losing three, four, five engines a minute under the defenders’ fire. Ironically, the legion that had once smashed Nurgle’s undead on the moon of Davin itself fell to Nurgle and fled to the Eye of Terror.

The first Titan Legion to go over to Horus and the Warmaster’s favourite. It broke through the Palace walls during the Siege of Terra (losing 30+ Titans in a single evening), then largely fell to Nurgle and fled to the Eye of Terror; to this day it ravages worlds under the tattered banners of Mortis.