Imperium take device room, realign Foramen

Having gained the knowledge to redirect the necron device, the imperium were keen to retake the device room and realign the Foramen as quickly as possible. With the imperial cult undergoing training by the Grey Knights and Konev recovering from the recent chaos advance in the east, the regular imperial army could not launch an assault against the centre of Praxis. Besides, a heavy handed imperial assault would likely face stubborn resistance from the entrenched chaos forces. A surgical strike was needed. 

The Ultramarines agreed to send in a small force, no more than half a company of astartes, to move swiftly and secure the main arterial routes - such as they were - and the device room itself. Meanwhile, the alliance had already landed, secretly, a small force of Librian specialists with their own plan to infiltrate the device room via the catacombs, while the forces of chaos under Stahl had replaced the unreliable orks with the elite units of the Iron Warriors, led by the “honourable” Horozhka. 

The Ultramarines easily cleared out the eastern and northern approaches to the device room, but on 1901.019M42 the ultramarines simultaneously encountered the elite Iron Warriors as well as the lead elements of the Librian stormtroopers who had made their way quietly around the catacombs and emerged close to the centre of the ruined city. 

The Ultramarines found themselves in a potentially deadly crossfire as the Iron warriors approached from their front while the Federal forces set up fire positions on their flanks. However, the Librian plasma fire was poor, many shots missing and those shots that did land near to a marine failing to penetrate their ancient armour. To the front, the Iron Warriors engaged in exchanges of fire with the loyalist marines, which did more damage, taking down at least two of their battle brothers with well placed heavy weapons. 

The Librians meanwhile took advantage of the bitter struggle between the astartes forces, moving forward in strength and engaging with the iron warriors on their right. Once again however their weaponry failed them, and they were unable to dislodge the traitor forces from their positions. On the left, inaccurate and ineffective fire blunted the federal assault, effectively putting an end to the alliance chances of securing the device room. 

The skirmish outside the ancient necron chamber reached fever pitch as the sun set on the city, with the Iron Warriors getting the upper hand. However in their eagerness to engage in close combat with their hated brothers, Horozhka’s squad took a risk, abandoning their strong positions in order to cut down their enemy. The gamble did not pay off, and the aggressive charge was held by the loyalist marines, and the iron warriors soon realised that their failure to deal with this squad quickly now risked other loyalist forces cutting them off from their lines. Reluctantly the chaos forces abandoned the centre of Praxis. The imperium now had control of the device. 

Within hours the Ultramarines had visitors from the Adeptus Mechanicus, who began their ministrations to the xenos artefact. By 2001.019M42 the work was complete and the Foramen Ignotum changed its alignment once again, condemning hundreds of supply ships en route from the Enceladus subsector to a horrific end as their ships were cast into the raging madness of the Cicatrix. The new alignment had created a new stable warp route to Ultramar. Now the device room had to be held, else any supply ships from the imperial held realm of Macragge would face a similar fate.