Originally posted by Beniboybling
Nai the Book of Anger as its depicted in the Book of Sith describes things differently:
If you'd read it carefully, then, no, it doesn't:
"It must be understood that anger can be funneled through the body and released near the heart at the "vital gate." The destruction that can be unleashed by this method is immense. Thousands of enemies can be annihilated in a single act of malice.In time, the channeled anger of the dark side will prove just as destructive as the Death Star. [...] Already, I have perfected the Force maelstrom [...] This technique can be increased into a Force storm. The churning energy mass of a Force Storm can consume everything it touches, for at its eye is pure hate."
--Book of Anger, Book of Sith
See the additional emphasis in the text. Once more, Sidious de-personalizes the ability, by operating with the "anger of the Dark Side" - not his own, personal feelings or force powers. The user of the ability is more a conduit for those things than an actual "user" in the sense of investing his very own power into the ability.
Evidently the power of the storm, attributed to "anger, combined with will" is that which is channelled and manifest through Palpatine's own body. And regarding the source that states Palpatine achieved mastery over this power:
The energy still comes fromt he outside.
Vast energy storms that connect wildly disparate spots across the galaxy, hyperspace wormholes are unpredictable and devastating. It was to the Rebel Alliance's detriment that Emperor Palpatine was able to not only control these storms, but to create them.--SW Handbook Volume 3: Dark Empire
You may want to have a look at the context. "Control" in this particular case is used as a synonym for "manipulate", contrasted with his ability to create them himself. That doesn't mean that he was in full control of the ability (since he could control them to a certain extend before, obviously).
@The_Tempest
Some of those instances involve characters becoming conduits for the Force and its will. Most other instances involve characters simply using Force energy for their own ends.
And which would be the case for Anakin, in the instances in which he did defeat Dooku, by merely imagining to do so or when taming Son and Daughter on Mortis? Were that expressions of his personal power or the Force acting through them? How do we seperate those instances and how do we rank Anakin accordingly?
Whether or not they are merely executing cosmic design in every scenario is unknowable and really beside the point.
Is it now?
In the context of using literature in order to judge the relative power-levels of fictional characters, I have to say, that I find it important, wether something is used as some kind of "deus ex machina" to save the day, or if we can expect that a character is capable of replicating feats, especially in the context of combat situations. Can Sidious summon a force storm with "universe busting abilities" at any given time or was it a result of his extreme emotions at that particular point in time? I don't have an answer for that question. Do you?
That the Emperor harnesses external energies and unleashes their power through sheer will isn't anything to note because that's pretty much how everyone uses the Force in general lol.
Is it now?
I remember the day, when a certain somebody attempted to talk down the instance, where Nadd's spirit collapses a cave on Korriban on Kun, by pointing out that Nadd merely triggered the release of energy being present in the place. I do likewise remember people attempting to talk down character feats by pointing to a "force nexus" or "dark side nexus", which is also just a place were there is more surrounding force energy than normal places have. Neither of that makes sense following your argument.
Furthermore you are quite wrong. May I point to the Fallanassi, who used the Force by manipulating what the called the "White Current" into maintaining desired effects (such as illusions) without further need of attention from the force user producing them in the first place? Luke later uses this methods to render an entire planet invisible for an, apparently, infinite amount of time.
And I view force storms similary: The user (e.g. Sidious) triggers an event in the Force (via a combination of anger and his own will) that then utilizes the Force energy present, independent of the force abilities of the original "user". Otherwise it doesn't make sense for the Force Storm to continue, when Sidious "lost control", being attacked by the Skywalker siblings. It should have vanished on the spot, instead of continuing and actually killing the guy who summoned it in the first place.
Another hint for the idea, that they are seperated from his personal force mastery, is the fact, that Sidious did even include those into his "Book of Anger", which was meant to share some parts of his knowledge and that, according to the "Star Wars Encyclopedia" (p.105), various Dark Side adepts were also capable of producing them - just having less control over the ability compared to Sidious himself. The same source mentions that even Jedi, banding together, could summon Force storms.