You are assuming that the characters know more than they do. You assume just because you are given some "inside information" at the end of the game that you already know the full story.
Quite the opposite - actually, I'm assuming that I
don't know anything - which is the problem.
If you come up to me and say "there's four things you need to make sure never get in one spot and into the hands of the bad guys," the very, very, very last thing I'd do is haul one of those things into the hands of the bad guys. I kept expecting the twist ending to be having Ghorr say, "thanks for saving me the hassle of getting the Crux of Fire the hard way."
(*) I didn't suspect The One existed - I thought Ghorr was behind the mind control - and so, therefore, did my character. In a land of magic, there's no reason to just assume offhand a Taurax can't behind the mind control -- he may have found the Mystic McGuffin of Foo which allows him to do things beyond normal Taurax capacity. Which is why killing Ghorr should have seemed sufficient. In fact, contact with Julian, Wendy, and Sparrow is totally optional - even if those contacts explicitly told me Ghorr was a pawn (which they didn't) - I still have every chance of getting near the ending without knowing that anyone is behind this
except Ghorr (minus the meta-game knowledge that obviously someone else has to be the bad guy for the sequel).
My actions make
more sense once I know the ending - but
before the ending when I was ignorant, I kept screaming "why the heck am I doing this? this is dumb!"
If you kill General Ghorr and leave, another would simply take his place. Ghorr isn't making the decisions, “The One” is.
Before meeting Shira, for all I know, Ghorr
is the One. For the reasons I explained above in the starred paragraph.
Do you really think "The One" would let you survive, or keep your free will after your assault on Talushorn?
What does he care for Talushorn? His home is elsewhere.
Thousands of individuals are under his influence. Wouldn't they just destroy everyone after he left? I don't know the details of how mind control works with regards to “The One”, but were he to die, would everyone under his influence be free from his taint?
I don't know the details, either - but
if the mind control requires
any effort on his part, then, yes, the mind control should cease, for the simple reason of: "what does he care?" why contribute effort to something you intend to leave behind as trash?
Oh, sure, he might just be comically, over-the-top, exagguratedly evil in the "I wear a black hat and I'm proud" way enough to just mind control civilizations to kill each other just to watch the guts spill - but I take BW as a better writer than to have such a 2D evil villain. Assume his actions are rational - that he really does just need 2 drive stones to split and all the war is just because he considers us so many bugs in the way of his acquiring them, and, then, yes, the main threat to this world (that we know of. at the
end, but not before the meeting with Shira) leaves with him.
Destroying the crux in Amireth is a good idea because no humans or dwarves live there, and Korren tells you there is a high chance a massive explosion will occur when the crux hit each other.
Even so, it seems smarter to leave the Crux of Fire with Korren while I go clear the place out - that way, if I die/fail, the Crux isn't
automatically in enemy hands. They still have to attack Mistfell, which gives Korren a chance to hide it (no, I don't "know" Korren is a good guy, but my character seems willing to trust him enough to take on a suicide mission, so why not trust him enough to hold the MacGuffin in case said suicide mission fails?)
I'm sure someone could devise a spell to raise the crux back to the surface. It wouldn't be hard, after all each crux is unique.
I have no idea how hard it is to make new spells, beyond that it's not easy enough for my character to do. So I can't say "wouldn't be hard" to overcome 10 kilometers of depth and a hundred Mega-Pascals of pressure without more knowledge of how the world works. I
do know the hiding it "well enough" seems to be an impediment to finding it (at least to people of this world - the only people I know exist before the last few minutes) because otherwise they wouldn't be griping about the Crux of Terra being in parts unknown.
And "The One" has technology not of this world which would help.
A fact which I'm totally ignorant of until the last few minutes, so it wouldn't enter into my planning for the assault on Talushorn.
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side note: do you know what happens if you leave the Crux of Fire somewhere safe before entering Talushorn level 4?
I do. The answer is "Nothing". The game ends the same, as if you were holding it, even though it's actually in a barrel far, far away.