So, I had some ideas for where Pandora should focus her efforts after we get back to Terra. It's arguably a bit premature since this campaign isn't actually even in the end stages yet, but the current vote is already a landslide and we can't meaningfully plan our next campaign turn until we get the next tactical/tarot update on where things stand after the coming update. So now's as good a time as any to start floating some ideas for our next Council/grand strategic moves to see how the thread feels about them.
I have three primary priorities that I believe Pandora should pursue next Council turn, each of which is meant to work synergistically with the others. I'm going to list them roughly in order of priority. Sorry about the length - as per usual, this ballooned from what was in my mind once I started writing it. I'll try to put a tl;dr at the end for those who don't have the stomach to read the whole thing.
1) Time for a new Ecclesiarch. Forcing out the worst eggs among the High Lords is explicitly noted as one of the two main ways Pandora boosts the amount of Influence she has long-term. The Ecclesiarch should be our priority target for this. There are a number of reasons why.
One, he seems to see Pandora as an opponent/enemy. That's a pretty straightforward reason why replacing him would boost our Influence and reform efforts.
Two, the Ecclesiarchy is the second-most politically powerful organization in the Imperium, after the Administratum. Notably, it's also typically one of the very most dogmatic and conservative factions. To make it even worse, the upper leadership is appallingly prone to personal corruption, dangerous zealotry, or both at once. If we can spend our Influence to get a sympathetic reformer in there instead it would be a huge coup for the nascent Pandora Bloc on the Council, significantly more so than doing the same with any or almost any other faction would be.
Three, the fact that we've been performing "miracles" left and right on this campaign, deploying dozens of """Living Saints"""*, and generally wowing the hell out of the Sororitas in particular, works very much to our favor in terms of pushing for Ecclesiarchical reform/replacing the current incumbent. The Sororitas are probably the most venerated people in the Imperium - they don't overtly hold the reins of the wealth and influence in the Ecclesiarchy, but they hold a huge amount of its moral authority. And everything the Ecclesiarchy has - the wealth, the influence, all of it - ultimately stems from its claim to possess the highest moral authority in the Imperium. If a huge amount of that moral authority is swinging towards us already, that gives us a lot of leverage on pushing for change in the Ecclesiarchy in particular.
Four, this is by far the best chance we'll have to get to get Pandora's existing worshippers legitimated as acceptable under the Imperial Cult. So that the Imperium we're ruling will finally stop burning our own goddamn followers as "heretics." That's a HUGE deal in its own right, IMO.
2) Truce/alliance with the Eldar. This is a good time for this for a few reasons.
One, the Eldar - well, y'know, the non-Drukhari Eldar - are perhaps the most likely to be both willing and able to help the Imperium. They're capable and have abilities and assets that Imperial forces typically lack, and they're the most likely to see that they need us as much as we need them.
Two, historically one of the biggest problems with forming alliances with the Eldar from an Imperial perspective is the huge edge in Divination the Eldar have on the Imperium. It makes it very hard to know whether you're getting a fair deal and a real alliance with them, or if they're just manipulating you because they can see the future and you can't. The fact that the Imperium knows this does a lot to taint any dialogue that's opened with them right from the start. But with Pandora around, that gap in Divinatory ability is gone whenever she's involved personally, and shrinking steadily in general with her tutelage of the Imperium's psykers (speaking of, that's one of the reasons it would be a good idea to invest time into training up the hundreds of thousands of psykers with the Expedition on our way back).
Three, the OTHER biggest problem historically with the Imperium opening a dialogue with the Eldar - or any non-humans at all - has been the Imperium's reflexive dogmatic hatred of all "Xenos," which for most of the Imperium stems directly from the Ecclesiarchy's teachings. Remember when I said these priorities were meant to synergistically work together? Effecting Ecclesiarchical reform in Priority One would make this option a lot easier/more viable to pull off. It'll also do the same for any other friendly actions we want to take towards non-humans, which is one of the big reasons why Ecclesiarchical reform comes above this in the priority order.
Four, the Eldar also represent one of the biggest opportunities for Pandora's Warpy expertise and powerset to directly fuck over the Ruinous Powers. In canon, the Ynnari are trying to wake up/resurrect Ynnead, but they're struggling because they either need to get one more Cronesword that happens to be under lock and key in Slaanesh's own palace in the Warp, or figure out an alternative way to get the power and/or ritual components they need. Pandora is probably the most likely out of anybody in 40k to be able to either come up with a way to furnish the juice, or use her Warp-stealth powers to pull an eldritch heist and yoink the Cronesword. And bringing back another Eldar god would be one huge kick in the face for She Who Thirsts - this is probably the best direct blow to the Ruinous Powers we could potentially be able to deliver in the near- to medium- to potentially long-term foreseeable future. It would also hugely indebt the Eldar to us if we were instrumental in it happening, which would be an amazing way to solidify the alliance.
3) See if we can wake up Guilliman. This one would presumably be a personal action, since IIRC that's what it was offered as last time? It's fair to ask "what do we need Guilliman for, when we've already got a Lord Commander?" And there are a few reasons.
One, the Imperium doesn't need another Lord Commander, but Panda could use a Warmaster. The Imperium is still in an ongoing state of extreme military crisis, and besides the obvious inherent good of saving lives and protecting Imperial worlds, the less personal attention we need to give to that then the more effort we can direct towards reforming the Imperium itself. It will be hard to make the headway we'll want to make if we need to be out leading Expeditions all the time, and spending our Influence on unfucking the Imperium's military response. There's basically no one we could plausibly get to take over coordinating the war effort as a whole who would be better than Guilliman.
Two, at least by the standards of the Imperium Guilliman is very reform-minded himself. In canon, when he woke up he came back to Terra and communed with the Emperor much as Pandora did in-quest, and much like Pandora he found that while the Emperor was concerned for the survival of the Imperium as a whole he didn't give a shit for the wellbeing of individual human beings at all. The conclusion Guilliman drew from this boiled down to "even if he really is a God, he doesn't deserve worship if that's his perspective." That's huge. You'd probably be hard-pressed to find even one other person of power in the Imperium who thinks the same way. That will paradoxically make it both harder and easier to get Guilliman to follow us - he won't have the automatic religious reverence or conferred loyalty stemming from our personal relation to the Emperor that others do, but he'll be more likely than almost everyone to be persuaded by our ideals. Guilliman strove for good governance in his original life, too - even now, the Realm of Ultramar is noted as one of the best places to live in the Imperium. That's a very relative standard, but it's still significant. He's also near-certain to be more likely than most to share our interest in reining in the excesses and dogmatism of the Ecclesiarchy. All in all, Guilliman would make a very useful and effective ally for Pandora.
In particular, it should be noted that Guilliman is specifically famous as a tremendously gifted administrator. The Ecclesiarchy is the second-most powerful faction in the Imperium, but the most powerful is the Administratum. It's also one of the ones that might be hardest for Pandora to reform. Not necessarily because the leadership would be more resistant than others, but because the biggest problem with the Administratum is its sluggish and impenetrably Byzantine bureaucracy. And while Pandora has many wonderful and admirable qualities, being a genius of bureaucracy is not one of them. Guilliman is, though. Setting him to the task of unfucking the Administratum's structure in between his Warmastering duties could honestly be our best shot at achieving real reform in the Administratum.
Three, people have expressed interest in doing a 27th Founding of Space Marines sooner rather than later. The big reason why so damn many Chapters are descended from the Ultramarines is that Guilliman turned his aforementioned administrative genius towards the task of raising more Space Marines, with the result that there were an absolute shitload more Ultramarines than any other Legion. Other Legions had a recruiting world. Guilliman organized an effective and streamlined system to draw from five hundred recruiting worlds. If we want to raise more Space Marines, having Guilliman involved could do a lot to make that a bumper crop. He's also notably excellent at leading Space Marines in particular, so there'd be synergy with having him as Warmaster from that too.
Four, as aforementioned all of these are meant to work together. In canon the Eldar had a huge role to play in waking up Guilliman successfully, which is why Priority Two comes above this even though this would probably make a bigger impact if it succeeds - since we didn't spec into Biomancy we might not be able to manage it on our own. Having Guilliman well-disposed towards the Eldar because they directly helped in bringing him back could do a lot to boost getting the Imperium to actually effectively work together with the Eldar, too.
Tl;dr - in order, we should focus on trying to get a reformer in as Ecclesiarch (to boost Panda's Influence, loosen the ties of the Imperium's reflexive dogmatism, and get Panda's own cult legitimated), get an alliance going with the Eldar (to improve our military situation, set a precedent for large-scale longer-term productive cooperation with non-humans, and to potentially directly wreck Slaanesh's shit big time by helping get Ynnead up and going), and wake up Guilliman (to get a Warmaster, to get an effective reformer for the Administratum's problems that Panda's not well-suited to address, and to improve the performance and size of the 27th Founding when we do that).