Ayacmanik options:
Traumatize the Oversoul
Pros: Ayacmanik cease to be a threat to us, but we don't have to otherwise spend time and effort exterminating them.
Cons: Until it's complete the Ayacmanik will attack us anyway, which means we may still have to move to a war footing until the plan is finished, although I'm not sure how long that will take. Also, the Ayacmanik are still around, not a threat to us but still a factor worth considering.
Give Them Minds
Pros: Best case scenario, gain a massive boost to our labor and military efforts, not to mention whatever additional abilities they bring to the table. Perhaps the most humane option.
Cons: Uncertain what they would actually do with sentience; we may end up creating an even more dangerous enemy for ourselves; if it fails we may have to start over and try a different plan.
Control the Parasite
Pros: Adds their strength to ours without the bother of actually needing their consent. Keeps the Ayacmanik around but makes them useful.
Cons: As with Traumatize the Oversoul, provokes an all-put attack until complete. Debatably slavery?
Chains of Fog
Pros: Explicitly a big win button for Mochantia (although it's unclear how much we need one at this point). Adds Ayacmanik labor and military might, as well as making them intelligent and thus more useful. Maximum utility to us.
Cons: Definitely slavery. Actually may no longer be possible since we used our Seed of Fog? Requires us to uplift them first.
Burn Their Souls
Pros: Easy, clean way to exterminate some pests.
Cons: Triggers all-out war with the Ayacmanik. A weapon we have to use multiple times rather than a way to address the overarching problem. Not technically genocide, but feels sort of like it.
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Overall, Give Them Minds has the most risk and the most reward imo. Potentially creates a new, more dangerous enemy (although we explicitly have safeguards in place against this), potentially creates an extremely valuable ally. Or maybe the Rangdan will do something we don't even expect and we'll have a new problem to deal with. It does, at least on the surface, have the least amount of fuss.
By contrast Chains of Fog is difficult, messy, and amoral (not that the Lizardmen care, but I sorta do), assuming it's still on the table I'm not sure it's worth it.
Traumatize the Oversoul, Control the Parasite, and Burn Their Souls all provoke all-out war although at least the first two end the conflict early rather than giving us a second round of warring and sweep-and-clear operations right after killing the Orks. However, any of these three seem like equally viable solutions, with Control the Parasite being the one that maximizes utility to us.
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Ultimately I think it comes down to what role people think the Ayacmanik should play (in the Quest and in our Great Plan) going forward.
I think Give Them Minds could be really interesting in that it might give us a major ally, and one that is very alien, but could also create a whole bunch of issues we don't want to deal with. I can see why people would pass it over, but I mostly just want to know what the Rangdan would do with sentience.
Control the Parasite is the sweet spot between mess and utility, and I would probably support any plan that included that, plus it gives us a freaky hive mind servitor race that adds to our eldritch aesthetic. That said, if other people want to just get the Ayacmanik out of our way but leave them alive (Traumatize the Oversoul) or exterminate them entirely (Burn Their Souls) then I suppose that's acceptable.
EDIT: Actually I agree with
@Simon_Jester that a separate approval vote would be useful in sorting this out.