*Legends. There's not much reason to think Sithisis itself is canon, just because the Sith shrine beneath the Jedi Temple is canon.
However, even IF Sithisis were canon, I'd sooner think Palpatine was preforming said rituals at his base in the LiMerge Building on Coruscant, as opposed to underneath the Jedi Temple itself.
After all, we know for a fact that Palpatine canonically used the LiMerge Building to preform other, very powerful, Sith rituals/magic during TCW, so it would make sense for the rituals in Sithisis to take place there as well. Trying to preform rituals of that magnitude in a shrine just below the Jedi Temple would have been a bit too bold(even for Palpatine), and undoubtedly risked drawing attention from the hundreds of Jedi above. /shrug
And Sith crystals are infused with Dark Side energy.
__________________ RealistRacism: "Sheevites, much like the Banites, were meant to increase in power with each member. From Lightsnake to Gideon to Azronger, this was supposed to be the case. However, knowledge must've been lost in some kind of Gravid-like incident, as Az turned out to be a mid-tier debater with a sub-par track record, sh!itting all over Tempest's legacy. Sad."
1. That would suggest Windu is at least=Palpatine. And the novel clearly mentions that Palpatine blasted him using his full extent of power.
2. Second case Nyriss was on a Dark Side nexus and Revan's connection to the Force was weakened and he easily deflected an attack that would turn people into ash.
__________________ RealistRacism: "Sheevites, much like the Banites, were meant to increase in power with each member. From Lightsnake to Gideon to Azronger, this was supposed to be the case. However, knowledge must've been lost in some kind of Gravid-like incident, as Az turned out to be a mid-tier debater with a sub-par track record, sh!itting all over Tempest's legacy. Sad."
So your conclusion is that if someone isn't instantly turned to ash by force lightning, that they are equals or superiors even if they get severely damaged/killed?
Also the novel also created the "bending lightsaber" angle as well. Windu took this attack without being ashed. He is incredibly powerful. Not everyone can take the lightning as well as another being, which is the point. For whatever reason you think bringing up the Revan example helps your case here, when it only serves to highlight that fact.
So what you're saying is that if someone were powerful enough, they could take an ash rendering lightning attack without actually turning into ash? How far away from my original point.
Isn't this the very reason you say that Windu wasn't turned instantly into ash because he was so 'strong'?
__________________ RealistRacism: "Sheevites, much like the Banites, were meant to increase in power with each member. From Lightsnake to Gideon to Azronger, this was supposed to be the case. However, knowledge must've been lost in some kind of Gravid-like incident, as Az turned out to be a mid-tier debater with a sub-par track record, sh!itting all over Tempest's legacy. Sad."
Anyway, I'm saying that Windu was one of the most powerful Jedi of all time and apparently had a heavy lightning resistance of whatever that entails, hence "strong" is a good catchall to explain it.
Him not being ashed does not raise questions of other beings being ashed. That in itself is not enough to conclude something of which you did in your original post about ash.
Those 3 acolytes admitted Vader might have beaten them when they thought he was way below Darth Maul. They are nothing special. The ritual wyrm too, did nothing. Those feats in itself are not enough to conclude that Sidious was significantly amped and could never do it under normal power far away from Nexuses just because he failed to turn Windu into a skeleton. Bringing up Revan does nothing to change that fact. Bringing up Revan only highlights that there is some sort of resistance to that level of power.
I'm not saying Sheev was amped or not, but him failing to ash Windu doesn't make that clear is all. Nor can that be misconstrued into some sort of logic that makes Windu equal or greater than Sheev.