Sigmars time is so far away, and the circumstances of the Empires rise are mutable. It relies heavily on the specifics of a bunch of short-lived humans who appeared at the right place and right time with no overarching plans setting them in motion.
I mean just imagine if Soulcake decides to roll for what God Sigmar follows when he unites the Empire, and it gets a 1.
The Dread Emperor
The axe in his hand thrummed with power, a gift from the mountainfolk in ages past as it tore away the magic in this place. "They come; will you stand with me again on the battlefield old friend."
Fire rumbled forth in agreement. The wily old mammoth's eyes darting over the latest city they had reached too late.
The charred husk of the city of Salzenmund had long been reduced to kindling.
Smoke and ash billowed upwards in an endless expanse that blackened the skies in all directions, and from the chaos rose ranks upon ranks of demons. The rotten corpses of the dead rising once more, blood soaked monuments rising out of the ruins, a eulogy of songs and screaming carried on the winds and flashes of iridescent light pouring from the skies.
As one his men stood behind him, the armies of Norsca free of the taint of the Ruinous Powers, united in their pact with the elder races stood and prepared for war.
The steady thrum of the runes flowed as their power rose. The storm above surged to meet the devastation of their foes. The great shamans stood as one, pouring the winds of the aether onwards to assist their flying brethren.
Dwarf and man marched together in lockstep, even as the first of the artillery began to fire upon the dark tide awaiting them.
He stood at the front of the horde, a twisted mass of bulging red muscle and distended limbs.
Upon his back a standard of brass and iron poured blood in an endless tide, caking the very world around him in a miasma of Kharneths fury.
In his left, a whip danced endlessly as a thousand barbs tore screams from followers and foe on the whim of the Dark Prince.
In his right a hammer fit for an ogre wept a thousand pestilent maladies upon the world that cursed flesh and reason alike with the Plaguelords rot.
And on his brow a simple circlet of iron rested above eyes surging with the might of all eight arcane winds as the storm of chaos moved to the call of the Architect of Fate.
Everchosen Sigmar had come for them.
His own amulet of challenge pulsed with power. "I am Morkar King of the Norsii, face me kinslayer."
The Dread Emperor stared back even as the storm above fell upon him, a single hand reaching out and catching the lightning within. "Kinslayer?" His voice filled with mirth, even as a smile rose to his face. "Can you really call such weaklings your kin, the sycophants and cowards unwilling to grasp true power when they see it before them. Morkar you must realise we are like Gods amongst men, so why not take my rightful place above the masses?"
A wave of the monster's hand and the lightning poured forth, a flickering bolt of power that skittered harmlessly off his own shield.
He surged forward, strength filling his limbs and they met in combat. Axe and hammer, whip and shield bouncing off one another as the ground crumbled around them. "You're mad."
"I am enlightened." With an idle blow the whip lanced out and killed a man behind him. With a wave of his hand the winds tore the Brana above from the sky.
The hammer came down on the charge of a mammoth, the two combatants blown away by the force of their clash.
And in that moment his own axe swept in, wreathed in ethereal flame as it scoured the magic infusing the Dread Emperors form, rendering him mortal once more.
Fire answered and his world burst into flames.
