Prospero, located in Imperium Nihilus, had once been a human world as precious as a ruby.
Under the meticulous care of Magnus the Red and the Thousand Sons Legion, it had not only preserved vast knowledge from countless worlds across the galaxy, including Xenomorphic Races, but had also been the sole holy land in the hearts of innumerable psykers.
However, when Orbital Bombardment like heaven-scorching flames covered the entire land, and pyramids and magnificent libraries holding countless precious stores of knowledge collapsed into ruin, all that remained were a terrifying, charred, scorching surface. Lightning and psychic fluctuations churned endlessly, shrouding the wreckage of countless buildings.
In truth, even if you deeply understood the grave error Magnus the Red had committed, and even if that irreversible mistake had forced him onto the path of Chaos.
When it came to the destruction of Prospero alone.
You would still have chosen to stand with Magnus and the Thousand Sons Legion, rather than Leman Russ, the Wolf King, and his Space Wolves.
Because, in your eyes, what had been destroyed on Prospero was never merely a Primarch who had committed a great wrong, nor simply an Astartes Legion.
It had been the utter incineration, from the very root of the Imperium of Man's soul, of the drive to pursue endless knowledge and the curiosity to explore all unfamiliar things!
From that moment onward, humanity had fallen into an irreversible slow death. The Emperor upon the Golden Throne had merely forcibly delayed that death for over ten thousand years.
As time slowly passed, one massive White Scars vessel after another successfully arrived at Prospero.
The first sight that entered your and the Khan's field of vision was a desolate world filled with Chaos Psychic Energy fluctuations, endless flames and smoke, and ruins reduced to charcoal.