They were doomed, all of them. That much had been clear ever since the first moments of the betrayal. The Loyalist forces were outnumbered by an enemy that were man for man their equal. They were cut off from all possibility of support or reinforcement and the potential for them to be bombarded from orbit was a constant threat. Everything they did, every treacherous life they had taken was nothing more then a bloody minded act of stubborn defiance. But as the entrance to the catacombs collapsed around them and the rag tag loyalist force withdrew into the relative safety of the underground tunnels, Sebastian felt hope. If all those around them were able to accept the superiority and perfection of the 3rd Legion's strategy, maybe they would survive this after all. With a nod to Decurion Locolus, Sebastian turned and headed into the tunnel.
For all the safety the tunnels offered at this moment, Sebastian did not like it down here. The place unnerved him. Its strange twisted structure felt alien, its sunken statues and religious symbolism even more so. He sighed quietly. It was a shame that this world had turned from the light of Imperial Truth. Sad that this retribution had had to fall upon them and worst of all that the Emperor's Children as he knew them were now denied the glory of the worlds true destruction.
In the large central chamber they found themselves in, the other legion commanders along with the Mechanicus Priest were trying to scan the tunnels with little success. Both a blessing and a curse as it could be assumed that their enemies would have similar trouble using such devices to detect them.
He didn't like the Death Guard and World Eaters taking command. They were off roughly equivalent rank and to his own mind, Sebastian knew he would be the greater leader. He was one of the Emperor's Children after all. He knew though that Lieutenant Morturg especially seemed to know the tunnel system better than he or Tiberius would and for now, he would settle for following his lead. As the thought passed through his mind, the Death Guard Lieutenant started issuing orders, directing detachments of their force down seemingly random corridors. Sebastian saw not obvious system or sense to the deployments but right now felt it best not to start questioning them. Something about Morturg's voice over the vox made Sebastian sure. "Enemies." Morturg said.
Alongside Tiberius, Akkad, Kyros and some others he was less familiar with, Sebastian fell into line behind the World Eater Darr.
"Hands and blades." the Centurion ordered.
Does a World Eater ever use anything else? he thought. Oh of course, he forgot teeth.
Despite hill sarcastic inner monologue Sebastian had no problem with the instruction. He mag locked his bolter to his lower back and carefully withdrew Spectre. He raised it to a high horizontal stance near his right shoulder but kept it deactivated so that its glow would not give them away in the darkness. As the group slowly made their way through the twisting tunnels, darting from cover to cover, shadow to shadow they heard footsteps. It was possible one of the other group had been turned around or their tunnels had somehow linked, but Sebastian had learned by now not to trust anyone left on Isstvan III until he had good reason to do so. Before he could think about it too much more though, Decurion Locolus leapt into action, laying down his plan. With no objections, Sebastian remained quiet and moved to a position hiding beside his fellow 3rd Legionnaire.
As the World Eater traitors came by, eager to assist their supposed ally the trap was sprung. Tiberius a step ahead of him cut down a warrior with a precise blow of his spear to the enemies neck. Sebastian sidestepped his own target lining up in a low stance to the World Eater's right as the traitor raised his bolter. With the perfect opening, Sebastian trust Spectre forward, activating its power field at the last moment so the blade pierced the World Eater's power armour and his lungs and hearts alongside it. The World Eater fell to the ground and Decurion Aurellian stepped forward already aiming for his next target.