I was going to respond to this when it was initially posted, but was pressed for time.
However, AP seems inclined to construe this as some kind of game changer, which it really isn't, and has asked me to share my thoughts. So I'll oblige. 🙂
Note that most of this is essentially recycled arguments from SWTOR that AP has conceded to me in the past. First off regarding this quote from the JA sourcebook:
Exar Kun himself possessed a great many other dark powers that he was unable to harness without the energy he needed to fuel his disembodied will. Some of these powers he was able to channel through Kyp, Gantoris, and Streen to achieve his ends.
To paraphrase myself this statement is in a word, non-descript. Kun prior to this event absorbed the Force power of thousands of Massassi to empower his spirit, that may very well have significantly increased his capacity to wield the Force, as Nathema did to Vitiate.
Kun was also capable of many powers that went beyond his natural capabilities by way of amulets, ritual apparatus, Sith temples etc. and in his spirit state, was completely unshackled from mortal limitations, in particular having a logically infinite capacity to store Force energy.
Altogether it is neither implicit that these are powers he'd be, without any kind of aid, naturally capable of in life, nor can we assume these powers would be realised through that natural capacity when, for stated reasons, Kun is capable of going beyond his natural ability.
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Next let's address the claim that Kun needed "all" Luke's students to resurrect himself, an assertion that appears to be based on the following statements:
With a nucleus of followers to provide him energy-providing anger and fear, Kun will have enough power to escape his exile and take on human form.
Exar Kun corrupted Luke's most powerful student, Kyp Durron, and attempted to resurrect himself by draining power from Luke and the other trainees.
Except it's nowhere actually stated here that Kun needed all of them, merely that his resurrection involved Luke and his students, instead it's elsewhere remarked that:
Taken from Jedi Academy SourcebookA few scant years later, Kun is brought sharply awake by the arrival of not one or two, but a dozen humans blazing with the power he needed to live again.
Implying that rather than all 12, any
one of them would be sufficient to restore his lost power, it merely being a matter of finding a sufficiently pliable host.
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Finally, the assertion that "if he had regained that power via any means, he would have taken physical form", I'm afraid that that is an assumption, not a logical deduction.
What Kun wanted to do was essentially create a dark side avatar, a body, fashioned from the Force, in which to house his spirit. Logically speaking the creation of such a thing would require a considerable amount of power in and of itself, and we've no basis to assume that would entail more power than he ever had when he was alive.
And without physical form, Kun has no means of maintaining pre-existing strength indefinitely, hence achieving that state would be intrinsic to permanently recovering his lost reserves.
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Altogether I'm failing to see a valid premise for taking the feats Kun accomplished with aid, at face value as is being suggested. Instead let's review the circumstances of said feats.
First of all, when he put Luke Skywalker in a coma, where we should note the following:
Taken from Jedi Academy SourcebookOver a number of weeks, Kun slowly bends Kyp to his will, and begins to augment his power. He grows very powerful on Kyp's hate, and soon his hold on Kyp is so complete that he can send Kyp beyond the planet to do his will and still retain control over his subject. Ultimately, he has Kyp return to Yavin Four and helps him reclaim the Sun Crusher. He also bolsters Kyp's talents to allow him to defeat Luke and place him in a coma.
So when Exar Kun (and Kyp) recovered the Sun Crusher, and attacked Luke he was, at that point, "very powerful", while simultaneously augmenting Kyp's already profound ability that as AP points out, had the potential to rival Vader's if he turned to the dark side, which he did.
And it's only through their combined strength, by tag-teaming Luke, that he's defeated:
Taken from Jedi Academy Trilogy: Dark ApprenticeKyp stretched out both hands and blasted Luke with lightning bolts like black cracks in the Force. Dark tendrils rose up from the gaps in the temple flagstones, fanged, illusionary vipers that struck at him from all sides. Luke cried out and tried to strike back, but the shadows of Exar Kun joined the attack, adding more deadly force. The ancient Dark Lord of the Sith lashed out with waves of blackness, driving long icicles of frozen poison into Luke's body [...]
[...] Against the full might of Kyp Durron and the forbidden weapons of the long-dead spirit of Exar Kun, even a Jedi Master such as Luke Skywalker could not prevail.
Noting that Kyp's unlocked dark side strength, seemingly without Kun's initial aid, is itself capable of generating powerful lightning and dark side tendrils. And that this is the same "full might" that could toss freighters, manipulate black holes and is supposedly Vader tier.
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Which brings me onto another claim AP makes, namely that the Yavin 4 temples merely sustained his will rather than being sufficient to empower him. And while this is a reasonable assumption, it was not the case for the individuals that Kun channeled his powers through, Kyp for example taps into it:
Taken from Jedi Academy Trilogy: Dark ApprenticeHe reached out with his mind, following the paths of the Force that led to every object in the universe, drawing power from the cosmic focal point of the Massassi temple.
Noting of course that Luke confronts Kyp immediately after in this same spot.
Taken from Jedi Academy Trilogy: Dark ApprenticeThe Sun Crusher hung suspended over the temple, still steaming in the morning air, resurrected from its tomb at the core of the gas giant. Kyp Durron spun around to stare at Luke, his black cape swirling with the rapid motion.
A cosmic focal that Kyp knew how to tap into, not great odds for Skywalker.
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Now for the Streen showing, which it should also be noted, was also performed within this cosmic focal point:
Taken from Jedi Academy Trilogy: Champions of the ForceLeia suddenly knew what Streen intended to do to them, whether consciously or unconsciously. They would be sucked out of the Great Temple, tossed high into the sky, and then allowed to crash thousands of feet to the spear-pointed branches of the jungle canopy.
Now we can't say with certainty that Streen, like Kyp, was drawing on the temple for strength, but it's certainly a possibility.
More importantly however is the fact that Streen has an innate talent with Alter Environment, capable of for example, countering Exar Kun's Force choke, buffeting a massive Leviathan with a wind storm, and repelling plumes of lava. Evidently if that kind of talent is augmented by a powerful Force user like Kun, the results will be tremendous, but that doesn't mean that Kun, who lacks that innate talent, would be able to achieve that feat without that level of genius.
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Finally, in regards to the one notable showing he accomplished without aid, namely Force choking, what has come to my attention to be not just some of Luke's students, but all twelve, while they were employing a Jedi meld.
Now considering that with the powers of the entire Jedi Academy combined where able to Force push seventeen Star Destroyers out of the system, I think it stands to reason that if this feat is interpreted as AP and others have suggested, that it proves, again as AP and others have suggested, that Exar Kun can telekinetically dominate beings in excess of Galen Marek.
And of course we are supposed to interpret this as a low ending showing. 😬
Forgive me for being skeptical, when in life Kun was incapable of overpowering a pre-prime Ulic-Qel Droma. Yes, it's been raised that this was before Kun's own prime, but only by a year, and by which point Exar Kun was already fully seated in the dark side. And surely if we consider that Spirit Kun was supposed to be weakened, it really doesn't matter.
The logical explanation of course being that this is an outlier. ✅
Is this a reasonable assertion to make? Yes. Exar Kun as a spirit, is completely unbound from the mortal coil, there is therefore, in brief, no limitation to his ability to channel the Force at any given time. Given that, an explosive burst like this seemingly well beyond what he's been shown to be capable of accomplishing in life, as a last ditch attempt that left him seemingly utterly depleted (seeing as he's overpowered and sealed away immediately after), isn't necessarily outside of reason.
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And that ends my assessment, your welcome, AP. 🙂