I am so happy for the new Guard codex but one thing bugs me. No rough riders.
I had planned my force as a mounted infantry force, that would keep a small force mounted to support breakthroughs. It would help show the theme of mounted infantry fighting dragoon style.
Now that is no longer possible. I am considering adjusting the theme to the Soviet naval infantry forces "Black death" during WWII.
However, I just started reading The unremembered empire by Dan Abnett and learned about the Pharos device.
It struck me that since Guilliam has formed a special corps of scribes whose mission it is to try and create an as accurate as possible history of the Imperium he would also be considering archaeological style field research. Sure, the Mechanicus is always on the look for STC:s and also forbidden tech, but Guilliman may want to be more proactive himself.
So I figured a force that is actually really an escort force for such an expedition would be cool. Also, considering the fact that half the Empire is blacked out by the mother of all warpstorms that the Astronomican cannot penetrate, something needs to be done.
Although having himself ordered the destruction of the original Pharos, Guilliman knows that it most likely were part of a larger network. Could another one, or better, more than one be found?
For such a task you need a specific task force. Most likely you will want a force that can defend itself in case of trouble, yes, even make limited assaults if you need to actually capture something that someone else controlls.
Having an trusted Inquisitor from Ordo Xenos in charge seems like a good idea. The main combat force being an Astra Militarium battle group also good. And a small force of Marines from Scythes of the Emperors. A Mechanicum presence seem appropriate as well.