Umbra Mortis Stalemate

The Umbra Mortis Stalemate was an Imperial campaign conducted by the Omni Legion Space Marine Legion in the far reaches of the Segmentum Obscurus upon a besieged Imperial world located in the mysterious Halo Stars, that was under attack from an unnamed Necron Dynasty.

History
Far from any territory the Omni Legion typically deals with they would travel, to the Halo Stars. These orders coming directly from the Adeptus Mechanicus, to accompany Tech Priests of Mars during one of their numerous Exploration expeditions. This would take the forces of the Imperium to the furthest reaches of the Segmentum Obscurus and discover a previously unknown system with several unexplored worlds. Unknown to them it was under the ownership of a Necron Dynasty known as the Vexhi Dynasty. The world Verta 3 was selected first to be investigated by the Mechanicus so the Omni Legion dispatched their Veterans to the surface as a maximized security force.

Mere days would pass before the Astartes would encounter a trio of Doom Scythes that would fire upon the forces of the Imperium, it would take time for the Marines to fight off the fighters due to the lack of heavy armour support that was still in orbit. Taking only light damage the Scythes withdrew, giving ample time for the Imperium to recover from the initial attack. Over the passing days more and more Necrons forces would appear, Land Raiders dropped from orbit and aerial support in the form of Storm Hawks were used to fight against the returning Doom Scythes. Skitarii and Kataphron Battle Servitors would provide support for the Astartes.

Many weeks would pass, over a month, eventually 48 days will have gone by with the sound of Bolters and Gauss weapons would fill the air. Attacks consisting of Necrons falling back and returning not long after to attack from another direction, constantly circling and attacking the Imperium. The attacks becoming more violent and engagements going on for longer with the appearance of a Necron Lord named Ankhra. The Omnissiah's Champion would seek her out himself in an attempt to kill the army's leader and ensure victory. This would sadly not come to pass, not where close.

While the Formation's Captain led his Terminator squads into front line attacks against the Necrons the lighter armored battle brothers provided long ranged fire support. Land Raider slowly moving back as Imperial forces were forced to withdraw, the Mechanicus prioritized once their excavations were either complete or they were forced to conclude them early. The Champion charged the Necrons Lord, going as far as knocking her from her own Command Barge. The pair would fight a 1 on 1 duel for the next 2 days, neither taking a moment of respite. Eventually orders to withdraw would reach the Champion. Initially ignoring the orders he'd be wounded by Ankhra, a deep slash across his chest that melted through his plate. A pair of Honour Guards meant to protect the Captain would appear to the aid of the Champion, one despite his thick Tartaros Terminator armour could get cut down by the Necron Lord. During that time the Champion and remaining Honour Guard would withdraw together with the rest of their forces.

The world has now been deemed restricted to Imperial forces as it was determined to be under the command of an entire Necron Dynasty.