Lol, the Night Lords don't need a reason to spread fear and badassery through the galaxy. Don't know about the others, nor do i care.
Awesome to see some of the iconic canon characters being involved in this. It certainly raises the stakes. None other than the Lord of Death himself too. Be interesting to see how they will incorporate Mephiston into the game. Also, a potentially interesting nugget of information to consider. I may simply be being unscientific here, but it mentions that Arkhona is half the size of Terra and yet has the same gravity. This either suggests that it has an extremely dense core, or perhaps this is a hint towards the somewhat awry nature of the planet itself, as has been so hinted at. That or I've overlooked some fundamental scientific principle on gravity.
That would certainly be an interesting choice for the Traitor forces! Plots and schemes aplenty! And with McNeill involved in the writing, that may be a very real possibility, given that he has written Ahriman in the past.