The Null Myriad, also known as The Legion Inimical, the Magic-Eaters, and the Mortoi Auroris, are a Legion of Ossiarch Bonereapers that are dense with the necromantic power of Shyish, glowing darkly as they march under a shimmering and baleful aurora. 
The Myriad was the first of the Ossiarch Legions to take shape, being a dark experiment Nagash performed in the Age of Myth. However, as the Pantheon of Order considered them abominations, they were exiled to the Realm of Death's Perimeter Inimical - the most hostile and flux-wracked of Shyish's underworlds. They stood here across the Aeons, as unwavering sentinels that cut down protean monstrosity and chaotic invasion alike with no mercy. For this reason, the eldest of their number are so saturated with deathly energy that predatory spells avoid them, and the graveyards in which they walk writhe with unlife. 
When the Shyish Nadir was completed, and the Necroquake shook the Realms, Arkhan the Black offered Katakros his thousands of tainted Deathrattle skeletons as material to expand the host. Since then, the Myriad has marched across the perimeters of the realms, claiming vast swathes in an attempt to ultimately control the source of their magic. 
These Revenants glow with a dark and silent power - for they are mostly resistant to Magic. From both their time in the Perimeter Inimical and from the tainted Deathrattle bone, the Null Myriad are all but immune to arcane attacks, with some even saying that they could march into the Realm of Chaos itself and come out unscathed. Few can contest them as they build vast necropolises amongst the howling gales of magic, causing mortal foes to rapidly sicken and age around them.