Update 1 the Chaos Invasion of Decskull's Empire

 Cast of Characters:

Orks:

Decskull: Goff Warboss of the Ded Ard Shooty Tribe

Captain Rot Ear: Free Booter Captain of Da Fleet, an sometimes Ally of Decskull

Duo: Upstart Nob that often unsuccessfully challenges Decskull's authority. 

Chaos:

The Dark Lord: The Exalted Chaos Space Marine Champion and Lord of a Chaos Fleet

The Beast Master: Chaos Beastman champion, and servant of the Dark Lord. 

The Opening Salvo: Battle Fleet Gothic. 

On the edges of the system, a chaos battle group dropped out of warp to transit to another madeville point on the way to invade Imperial space. The Great Rift had isolated so many worlds from each other and so the Dark Lord would find easy prey.

However, the chaos fleet encountered Captain Rot Ear's free booter Navy, who were also in the process of trying to leave the system to find new worlds to raid and plunder. The clash resulted in two Chaos cruiser's being crippled before they were forced to disengage. 

At this point the Dark Lord realized that the orks infesting this system would have to be dealt with before he could go on to ransack the worlds of the Dark Imperium. 

Cruiser Clash: Victory to Orks!

The Destruction of BOD, Exterminatus, Battle Fleet Gothic. 

The Dark Lord's plan was to exterminate BOD, which was home to millions orks and most of their infrastructure. Once that was accomplished, the fleet would support a ground assault on Morkheim, which had been identified as a former plague world, which might hold ancient treasures which could be of some benefit in the coming fight against the Imperium. 

In the course of the battle, the chaos fleet took horrendous casualties. One chaos devastation class cruiser was outright destroyed when it was boarded by Captain Rot Ear's Terror Krooza and two other chaos cruisers were crippled while only inflicting limited damage on the ork fleet. However the Dark Lord's flagship was able to launch several bomber squadrons which promptly fusion bombed BOD, killing nearly the entire ork population and their infrastructure. 

Victory Chaos. 

The Invasion of Morkheim Begins. (Warhammer 40K 9th Edition)

With the Chaos fleet crippled, Captain Rot Ear and his free booter fleet made it very difficult for the Dark Lord to land sufficient troops onto Morkheim. So instead the Dark Lord had to rely on landing small contingents of his best black legion chaos space marines, while also relying on his warp magic to take control of the millions of zombies on that world. 

Deprived of any reinforcements from BOD, the smaller number of orks would be on the defensive. However, the orks had vehicles, heavy weaponry and a number of well defended forts which overlooked key intersections leading to the main ork settlement, which lay adjacent to the ruins of Morkheim's once great capital city. 

The war for Morkheim had begun...