I vote for Navigator's chamber (not Astropaths, these guys send messages between worlds and dont navigate in the Warp, khornates will more certainly need a Navigator to steer the ship in Empyrean than some Astropaths) As for food and water supplies - they can pretty well eat the corpses....
Alright, so we might need to also focus on extracting our navigator safely then. It would be easy to kill it, but that would leave us stranded here without the means to continue onwards. Also can't damage the chambers to much, if we plan on using it later, so no explosives leveling the room.
Very well. Btw, not all the khornates storm the armoury and the hangars if you look at the numbers of killed, several squads could easily be dispatched by the warband's leader to capture a Navigator...
It's very alarming to think we've not even killed half their number yet, and we are talking about retreat to the bridge.
That's why you have the second rallying point to thin their ranks a bit more - then you'll heavily fortify yourselves on the bridge and wait for the Necrons and Dark Eldar led by Jain Zar, that was my plan.
Honestly a second rally point could easily be a main corridor leading to the bridge. Several check points would be strung along the corridors leading to the bridge. Basically harassing and thining out the enemy ranks as they fall back to the final defensive position.
Could probably have the established defensive point in the main corridor being by the navigator, and thus we need to extract it, or risk losing our means of Warp Jumps.
Dammit now my mind is thinking of this whole potential side thing with the Archon who just wants to be entertained even if it means having some of his own Incubi slaughtered by a Space Marine as he watches. Then Victus talking about it. "I swear those blades were coated with something because it's been five years and that scar still stings."
Actually, @kanila , do you want the Lord Commissar to announce the next rallying point? Have the rest of us fall back there under your direction and stuff?