“Karagon” would probably be a sticking point there. The Halassurqs have some very specific things in mind for the Karagonds which they won’t want to carry out under foreign inteference. You’d also get resistance from the many Nyrs who have no desire to fall under the rule of their benighted, superstitious, gender-obsessed cousins. But it’s a not-implausible division of territory if you can clear out the other post-Thaumatarchy factions.
That will be possible–and a massive diplomatic achievement. As the Hegemony falls apart, the pressure in the Empire to launch a campaign of vengeance, paying back the centuries of “Karagond aggression,” will be hard to resist for any Halassurq ruler.
@Norilinde, belatedly, by “thinkable” (for the author) I did indeed mean “achievable” (for the player). Where the Hegemony has failed for centuries to make more than incremental progress in conquering Halassur, it’s currently hard for me to imagine any circumstance in which Game 5 could involve a successful conquest–especially as one of the other key factions has their own well worked-out vision for Halassurq relations, and you’d have to worry about them stabbing you in the back if you got overextended to the east. I suppose if I think a little more about the example Napoleon offers in our world, I might get inspired. 
Can I say here that I’m impressed by how much animosity you’ve managed to build up toward this mystery faction about which almost nothing is actually known in-game?
If they send you a Talisman. There are otherwise no known ways–not even in legend–of doing Theurgy without bloodshed.
Don’t forget that the Hegemony is at best an early-modern state. They likely don’t have a centralized blood budget, or for that matter a centralized cash budget covering the vast majority of the costs of administering their territory. State budgets are a technology that took centuries to develop, along with the skilled professionals that make them.
Whatever the future may hold for the gameworld, there will definitely not be a silver bullet appearing in these games in which supply constraints and the associated dilemmas are suddenly removed.