They had done the calculations. Gone through every possible scenario with the data and information that they had access too... and even ran a few 'What if' scenarios on top of that if the search for anything that might change the outcome that they kept reaching. Defeat=Certain no matter what they tried, provided that 'Defeat' stood for the continued free existence of humanity on the planet of Pentious.
Even with the most generous of calculations, the death of Target: Warboss Kracker'Laker would cause a period of infighting among the remaining greenskins, but the greenskins conquest had already gained enough momentum that a new Warboss would simply come to power before the infighting reached the critical mass to break the Orkish force up. It would buy time but... nowhere near enough for them to recover enough to change their outcome.
Once human survival was removed as a requirement through, the situation started to look a bit less
grim... for a given value of grim.
So it was that Arch-Explorator Gifonadis Friedeg found himself standing before the core of the final human held Forge on Pentious. Once, it had been the heart of the capital ship of their fleet before it had been repurposed to give life to a new bastion of technology and scientific progress. Now, he performed the rites that would cause it to consume everything that himself, his loved ones and friends had worked so hard over the years to build as it died forever.
Even as he performed the Rites, Gifonadis felt the need to suppress his emotions to a more manageable level; It would be an insult to his peers if he messed up the process by not being professional enough to avoid slipping up something this important due to being overwhelmed by his emotions. Yet... he allowed himself to feel them all the same, even if in their suppressed form. It felt... right to acknowledge them in what was likely going to be his final hours.
The Greenskins had not yet began their final assault. Sensors indicated that they were celebrating the battle to come in order to boost their already high morale. But if the fall of Forges Gamma and Delta had taught anything, it was that the rites of self destruction took time in order to be properly initiated.
In the case of Forge Gamma, it's loss held a more personal pain then most. Forge Delta hadn't been finished when the Orkish tide struck, but Forge Gamma had been... and because of that fact, Arch-Magos Cykand van Ci's faith in the power of human technology to stand against the xeno tide caused him to insist that the Forge Gamma could be held. That the Orks could be broken against the bastion and driven from the world. Cykand had always been an inspiring figure as the original leader of Explorator Fleet XXXIV and his unshakeable conviction that the Orks could be defeated had been something to rally behind...
It was such a shame that his faith ended up being misplaced in the end. By the time his leader had discovered this harsh truth, it had been too late to fully perform the Rites of Self Destruction. Granted, the damage he was able to do in the short time he had almost certainly brought them a number of decades, but even now the ruined Forge Gamma had been twisted and brought back to 'life' in a mockery of the Omnissiah's vision and will by the vile greenskins. Forge Alpha would not suffer the same fate.
In different parts of Forge Alpha, Archmagos Prime BH-885 was overseeing the final preparations for the battle to come. What remained of the skitarii that had endured the long war with the greenskins were performing final rites of maintenance on their gear while the surviving Enginseers and Myrmidons made peace with the Omnissiah in their own ways as they prepared for what was going to be their final stand. The remaining machines of war were being awoken for one last fight as the tech-thralls were being positioned to meet the greentide first when they charged the defenses and soak up both the charge and bullets.
The battle plan, such as it was, required fighting the Orks for every inch of ground. They would bleed the greenskins dry and when, at last, the Orks began overrunning the Forge, Gifonadis would complete the final part of the Rite and take as many of the xenos with them as possible. Since the Warboss and some many of his bigger orks were committed to this battle, the hope was that as many of them as possible would be caught in the blast and wiped from existence, cutting the head off a depleted horde and causing their forces to splinter and fight each other rather then press on to attack other planets.
A black box had been prepared and hidden away from Forge Alpha that would transmit a signal should another Explorator Fleet arrive. A history of their Fleet, their forgeworld... and why it was cut short. Gifonadis could only have faith that it would one day be found and their story known to Mars. It would be a disservice to those from his fleet that had died during this campaign and those who had taken up the mantle in their absence if their names and deeds were completely lost to history.
Thoughts of his friends and peers caused Gifonadis to reflect on his suppressed emotions, even as his body continued the process of the Rite. Sorrow was consistant, as being the last living techpriest from Explorator Fleet XXXIV meant that there was a lot of memories of loss to process. Friends, peers and loved ones who had given their all to get to them this far, both prior and after planetfall... only for it to not be enough in the end. Bittersweet memories surfaced from the pools of sadness and Gifonadis took what comfort from them he could.
Rage was also competing for his attention. An unending fury at the lives lost, their mission compromised and their works being taken and twisted by the brutish, stupid half fungi creatures that were called greenskins. It was insulting that the bane of Pentious was an ork with the utterly stupid
name of Kracker'Laker. The only balm was that if all went well, he would die with Forge-Alpha and no planet would ever again suffer the indignity of being victim to Warboss Kracker'Laker again.
And this was the moment in which the Forge itself seemed to shake as something
big impacted... somewhere.
For a moment, pure terror gripped Gifonadis's heart and tempted him to trigger the destruction of the Forge... but logic and reason managed to restrain him as he opened the vox channel to the Archmagos. "[What is going on up there?!]" He barked in binary.
"[Trying to work that out.]" The much younger BH-885 answered back. "[We're getting mixed reports but...]" There was a pause of four seconds. To a normal human this would be something to note, but for the speeds at which the followers of the Omnissiah could share information it was a literal lifetime and a matter of great concern. "[...You're not going to believe this.]"
The final moments of Warboss Kracker'Laker were, in fact, captured by a servoskull that was spying on the orkish war camp to alert Forge-Alpha when the assault would begin. While the skull itself would be destroyed, the footage was recorded and kept both for important historical reasons... and because it was hilarious for those who had endured the horrors of the Warboss for years.
The footage starts with Warboss Kracker'Laker seated at the center of the orkish festivities when an Ork whose name was unknown but its appearance suggested that it was an orkish psyker (or 'Weirdboy') of some age due to its size. The start of the conversation is lost due to distance and the general noise of orks, but both those problems disappear as the Warboss suddenly slammed down a fist onto his table, shattering it as he shouted "W'AT DID YOU JUST SAYS TO ME?!"
While the other orks were stunned into silence by their suddenly loud and angry boss, the pskyer ork didn't seem phased in the slightest. "I SAID, YOU DEAF GROT, TAT WE JUST HAD A VIZION OF YOUR IMMPENDING DEFEAT! TAT STAR IN THE SKY-" and there was a pointed gesture skyward "-IS A OMEN OF YOUR DEAT'!"
As the Warboss rose to his intimidating size to clearly beat the living shit out of the orkish psyker, one of the bigger orks (or a 'Nob' as they are called by their own kind) was looking towards where the Psyker had pointed before saying loud enough to be heard in the silence "...Is it just me or is tat star ting getting bigger?"
In the four remaining seconds of footage, all the orks in view look skywards... before a bright, burning light enters sight and the footage ends. Slowing down the footage and using techniques to clean it up/dim the brightness of the light, it is possible to see what is clearly some kind of advanced, man made pod enter the line of sight of the servoskull, wrapped in the flames of reentry. One can also see the dumbfounded look on Warboss Kracker'Laker's face as it slammed directly into his head, taking it off before impact ends the footage.