Ok, got a plan together. Some options could end up switched, but the main things are going Fast, getting Exterminatus, doing the Siren trade, and warning the xenos but not warning Chaos.
[X] Plan Fast Conquest
[X] Fast- deploy ten billion men, take the Ork domains in an estimated 23 years, medium chance of something going wrong, estimated 25-50% casualties- The Inquisition, Champion Surt and the Security Council are pushing for this option claiming that urgent action is needed
The earliest that the Orks will go into overdrive is 30 years from now, and if we don't have the Ork Domains fully conquered by then we're going to have problems. We need to strike hard and fast.
[X] Reverse-Engineer Exterminatus Weaponry and then use stealth ships to use as many as possible on Tugozak's Domain- This would take at least a decade of Archmagos Tranth time and require a good deal of high quality materials, if successful it will reveal a great deal about the Imperial Trust capabilities, if successful it will inflict massive damage on Tugozak's Domain and render many worlds uninhabitable.
[X] Have Muspelheim Fleet harass Tugozak's Domain starting when Ork Domains are conquered, killing what ships and population centers it can- Inflict light damage, suffer light losses
[X] Have Vanaheim Fleet harass Tugozak's Domain starting when Ork Domains are conquered, killing what ships and population centers it can- Inflict moderate damage, suffer moderate losses
[X] Have Avernite Elites deployed to sabotage and destroy as much as possible, starting when Ork Domains are conquered- Inflict light damage, suffer moderate-to-high losses, increase any damage done by harassment fleets
[X] Have High Grandmaster Ridcully spend some time increasing the intensity of civil war in Tugozak's Domain- increases success chance of other attacks, inflicts medium to-major damage, increases strength of surviving Orks, ties up half of High Grandmaster Ridcully's actions for extended periods of time
[X] Have naval task force set out to inflict as much damage to minor worlds as is practical, starting after local Ork dominions are destroyed- destroy many Ork minor worlds fleet capacity and infrastructure, inflict major damge to most minor worlds populations, light losses
[X] Have combined armstask force set out to inflict as much damage to minor worlds as is practical, starting after local Ork dominions are destroyed- destroy half of Ork minor worlds fleet capacity and infrastructure, inflict major damage to half of minor worlds populations, light-to moderate losses
We shouldn't focus on anything other than conquering the Ork Domains near us until that's complete. After that we can start biting chunks out of the minor worlds and Tugozak's Domain, and we should hopefully have the Exterminatus weapons figured out at that point - better yet is that we don't start using the Exterminatus weapons until we're closer to the Orks going into overdrive, at which point other people will have less time to react to our use of Exterminatus weapons (and the context of us using them will become clear to them in a few years time).
[X] Feed Avernite Cultists to Sirens for knowledge
-[X] Spend 4 opinion each convincing Governor Garp and Lord-Marshal Sigurd to support the proposal.
As I've been saying, this is the best chance we're going to get at this without it being a complete and total political clusterfuck. It's already bad, and without an emergency to at least make this look like us being willing to do it because we're desperate the political costs will be much greater. Right now this is viable, doesn't cost us too much politically for what we're likely to end up getting out of it, and could end up being something that makes future daemonic incursions much less problematic, among other things.
[X] Contact the Eldar and Necrons to warn them about the awakening of the Ork Gods
[X] Do not warn local Chaos polities about the awakening of the Ork Gods
Warning xenos is something I think we can all agree is reasonable and necessary, and isn't so opposed that it costs us politically. Warning Chaos on the other hand is not politically viable, especially if we're doing the Siren trade, and costs more politically regardless. So no, not warning Chaos. Some of them will likely get forewarning anyways.