Sabius and Geltus ascended as the very earth beneath them split to reveal Ferrum Umbra's secret weapon. The warlord class titan clambered to the surface from its subterranean holding dock.
"Arise, Ferrum Mundi, ender of worlds!" Said Ferrum Umbra as the titans twisted metal frame creaked and cringed with every movement like an arthritic old man rising after a long slumber. As if sentient, the warp machine growled a mechanical roar, or so it seemed, as its Ardex Defensor bolt cannons roared into life and began cutting down everything across no man's land.
"Take it out!" Voxed Karagon as the blue arcs of plasma cannons bounced off the titans void shields.
"Void shields!" Came the response. The Red Scorpions had not anticipated a titan.
"Though we should have." Apothecary Zargan thought privately.
The traitor cultists and heretic astartes renewed their charge against the Red Scorpions, forcing them back towards the trenches that the Death Korps had once occupied and were now doomed to be enshrined in. Brother Geltus found himself already there, having fallen from the titan as it ascended to the surface of Ryboth; unable to make purchase and hold on due to his dreadnought armour.
"Sabius." Voxed the siege dreadnought.
"Up here!" He replied. Geltus turned. His battle brother was atop one of Ardex Defensor bolt cannons, under the void shield!
"The void shield must have fully activated after the titan was fully unshackled from its moores," said Sabius as he mag-locked himself to the behemoth and hacked away at the shoulder mounted weapon with his power sword until the bolt cannon sang no more.
Alarms and sirens began whirring around the titan as it registered the damage Sabius had dealt to it. The information data scrolled across Ferrum Umbras auspex. Cargore received the status update too.
"Secondary weapon inoperable." He voxed as Ferrum Umbra's frustration grew visibly.
Ferrum Mundi's arsenal was relentless. Even with the bolt cannon out of commission, the warlord titan's Belicosa Volcano cannons more than picked up the slack as they lay waste to Imperial's and traitors without discrimination. Ferrum Umbra looked up and saw Sabius atop the titan and struggled to contain his fury.
"Iron within." He incanted as he gunned the power field to operate his power axe.
"Brother Sabius," voxed Geltus. "It appears the traitor champion is seeking an audience with you." And with that, brother Geltus slowly began to make his way toward the titan.