In understanding Oracle level Entropy magick, one has to first look closely at pre Oracle Entropy magick, and gauge how the Entropy Mage's knowledge both increases in complexity and domain. From this pattern, we can discover the nature and domain of the Entropy Oracle's power. Primarily, Entropy concerns itself with order and chaos, having domain over both; an entropy effect can both increase and decrease the Entropic levels of the target. As the target becomes increasingly subjected to the forces of Entropy, it starts to lose cohesion. The Pattern begins to break up, and it decays. In this way, entropy could be considered the antithesis of Pattern magick, the Destructive to the Constructive, but that is really only highlighting half the picture. The first question to confront is to determine the actual boundaries of Entropy and whether the negation of decay can be considered something akin to creation.
If you look at Entropy Magick subjectively, the Entropy 3 effect to cause a negative Entropic effect to occur, that is for the Entropy effect to breed order instead of chaos, is not actually a negative Entropic effect. A truly negative Entropic effect would create something, which falls under the domain of Pattern magick. In effect, the 'negative' entropic effect is just stymieing the natural entropic process, and isn't 'creating' order. It is, in fact, stopping the inevitable entropic process that all things eventually become subject to. Thus lies the boundary of Entropy. The closest Entropy can come to 'creation' is the negation of destruction. It can prevent decay from occuring, but can go no further than that. The destructive side of Entropy is best described as controlling the rate of decay; the ability to either help or hinder the natural destructive process.
But this in itself is not a full definition of the domain of Entropy. The fundamentals of Entropy can be concieved as including Randomness or Chaos, Order, and Decay(Fate could be considered as randomness over a period of time, whereas fortune falls under the category of randomness). The Entropy Mage gains domain over the forces of Chaos with the second level of entropy, which concerns itself with probability. A 'random' event is merely an event that occured without any planning or forethought. Thus, the entire concept of 'randomness' revolves around the observer of the 'random' event. The events that caused the event to occur would have still transpired whether the observer was there to witness it or not, and the labelling of the event as 'random' doesn't affect the nature of the event at all - it just means the observer doesn't know why it happened.
[Maccabeus' note: Personally, after considerable examination of what the Mage book says about Entropy, I feel that this rather shortchanges the concepts of Fortune and Fate. The control of Fortune implies the control of "luck", that which is randomly determined (related, but not identical to, the concept of Decay, insofar as the more damaged an object is the more randomly its parts behave). The control of Fate implies the control of predetermination, that which is determined by events that have gone before (related, but not identical to, the concept of Order, insofar as the more whole an object is the more predetermined the behavior of its parts). In other words, the Sphere of Entropy is also the Sphere of causation; an Entropy mage can bestow a destiny on an object, which it will tend to fulfill regardless of what anyone does to it (when done on a person this is called a Geas); he can also remove a destiny even if it is determined by the normal processes of causation, making an event more random.]
The entropy mage, however, knows that the amount of 'randomness' that affects an object is determined by how much Fate is interested in that particular object. The amount of entropy inherent in it determines it's rate of change - the more entropy, the more change. As such, randomness is the cause of Decay and Order. If an object is not subject to entropy, it does not change, thus negating decay or improvement. (Note that Entropy can cause improvement as long as it does not involve anything new being created - that is pattern magick. An entropy mage can improve something if that improvement merely entails a re-arrangement, which falls under the category of Order). If the object has a lot of inherent change within it, it will change and, as improvement without conscious intervention is not as probable under the current paradigm, it will decay. Thus all three concepts; chaos, order and decay, are all a result of of the same force; Entropy - the force of change.
Now, as the Sphere progresses, the Entropy mage learns to control the effect of entropy on increasingly more complex and abstract forms. Level 3 offers the Entropy mage rule over the order of the simplest of the patterns, Matter and Forces. With level 4, more complex Life patterns are controlled, and with 5 the jump from the physical to the abstract is jumped with Intellectual Entropy. So it would follow that, as the magi progressed into higher levels of Entropy, the targets would become more and more abstract. At each level, the mage can control the way entropy affects this increasing sphere of influence. Once the third level of entropy has been reached, the mage has control over all of the fundamental concepts of entropy. Further progression only increases the mage's sphere of influence. So, here is a breakdown of what each 'level' of spheres beyond the Mastery level contain :
The mage at this level passes from the physical realm to the realm of Spirit, learning how objects and concepts lose their spirituality and spiritual significance over time, and eventually fade from significance. Note the Spiritual Decay of society since the Technocracy came into power - as Humanity stops nurturing it's spiritual side, the forces of Entropy continue eroding away at humanity's spirituality. In essence, eliminating the constructive 'events' to allow the 'destructive' influences to continue unhindered. This brings the other side of Entropy into focus – the lack of 'maintenance' of Humanity's spiritual side could be averted by putting more of an emphasis on the Spiritual. The Entropy mage gains the power to corrode or maintain a Spiritual entity, be it a Spirit, or the Gauntlet, or someone's Faith, etc...
The forces of the Nephandi are especially partial to this level,as it can be utilized in the corruption aspect of their paradigm - destroy a beings spirit, and it soon falls into their power.
Willpower also falls under this level, and for every success the entropy mage makes in their effect roll, one point of temporary willpower is removed from the target. When the target is out of willpower, the entropy mage may then start wearing away at the target's PERMANENT willpower. A number of success equal to the targets willpower rating will drop their permanent willpower rating by one.
The mage moves one more step towards the abstract with this level of knowledge. The mage can now work Entropic effects on things that normally are not subject to the forces of entropy, those being the very abstract structures of reality - Correspondence and Time.
In Correspondence, the mage works Entropic effects on the correspondence point, withering dimensions and destroying locationality. The entropy mage can wither the 'xth' dimension of 3-dimensional space on an area, reducing the area to a 2-dimensional space. The mage can destroy 'parts' of the correspondence point, creating correspondence anomolies where nothing exists or can exist. They could also re-inforce the correspondence of an area, allowing for less and less inter-dimensional interaction. Using 3D space as an example, using a Entropy 7 effect to strengthen the 3 dimensions, it would be harder to 'move' along multiple axes. It would be difficult to move back-and-to-the-left, or up-and-back-a-bit, until eventually only 6 directions could be traversed - right, left, forwards, backwards, up and down.
With Time, the mage is more limited, and very large Paradox Spirits tend to get upset when segments of the time-stream are 'cut'. With conjunctional Time 2, the mage can 'remove' segments of the time-stream. Paradox will not allow for a 'hole' in the time-stream, so time will seem to 'skip' at the erased area. Memories of the segment in question will fade from existance, events that occured in the 'erased' area will not occur, etc. The repercussions of this deletion may be far-reaching indeed. This is a sure-fire way to get some really big Paradox spirits down your pants.
Conversely, re-enforcing a segment of the time-stream would keep that segment of time 'fresh'. It would be easier for people who were around in or learned of that segment to remember it, etc. Also, using the theory that time exists not in a stream but as a series of branches, or an infinite number of parallel streams, with each branch focusing on an event in the previous branch, or each stream being different based on the different outcomes of certain events, the mage could make one of the event-possibilities 'less likely', or 'more likely' to occur. They could wither away branches, making events that were previously improbable truly impossible.
With Prime, something about the mechanics of Entropy must be understood. When something is destroyed, the Prime that fueled its existance is 'recycled' back into the Universal Prime Pool. The 'natural entropic process' that decays all things is the tendency for prime that has been 'removed' from this pool, bringing 'things' into existance, to slowly but surely return to this pool. With this level of knowledge, the Entropy mage can skip all the rigamarole with decaying a pattern until it loses its cohesion and having the Prime return of its own volition. The Entropy mage can now just recycle the Prime, returning it straight to the Universal Pool. With no quintessence fueling its pattern, the object is removed from reality. (Check out Prime 4 for a good analogy.)
With this level, the mage now has no loose ends in being able to destroy 'things' from reality, regardless of their origin. The mage can destroy pretty much anything of a tangible, intangible, or metaphysickal nature.
[Maccabeus' note: This would include, though Gil doesn't mention it, the erosion or strengthening of acts of magick (or magic), mainly including Correspondence- or Time- hung Effects. There seems to be very little treatment of meta-magick in the context of Mage, resulting primarily in a very poor showing on the Sphere of Prime.]
Conversely, the mage can 'strengthen' the bonds of existance a 'thing' has. By playing the flow of quintessence to a Life Pattern, the mage can increase (or decrease) its chance of contracting diseases, having heart attacks, etc. It can act as a 'barrier' against someone playing around with its quintessence flow(a la Prime 2-5) by making it exceptionmally hard for the quintessence flow to change.
At this level, the mage gains the ability to 'turn back the clock' of Entropy, thus breaking the fundamental law that determines the sphere of influence any entropy effect has. They can put the Entropic process in reverse, restoring a 'thing' to its original form. A chair that has been weathered and used and is generally beaten up can be magickally 're-vamped', restoring it to its original shape. A neighborhood that was once a happy place, but has since been turned into a crime-ridden slum due to Spiritual Entropy can be have its sense of community restored. The same can be done to anything that has corroded or decayed, be it physical, metaphysical or abstract.
This level could be viewed as a big version of Entropy 8, but should be viewed as the be-all and end-all of Entropy. Whereas with Entropy 8 you could destroy things one at a time, more complex concepts such as towns, or holidays, or celestial bodies or the like could only be destroyed by removing their components one at a time until there was nothing left. With this level of understanding, the mage can destroy the vaguest concept.
Say, for example, the Grinch, a Nephandus 'Oracle', decided he's had it up to ying-yang with Christmas, and he's going to exercise his newly-discovered Entropy 10 effects to just write the damned thing off once and for all. Before, when he had only Entropy 8, he would have to erase the memory of Christmas from everyone who knew about it, destroy all the memorabilia, destroy the spiritual, warm-and-fuzzy feeling people would get around Christmas-time (what was left of it, anyway); he'd just be spending far too long on a nearly monumental task. Now that he's achieved this level of Entropy, he can work this effect on the concept of Christmas, erasing it from existance. He'll probably need help, and it'll take a lot of time, but he can feasibly do it now.
Let's also say, for example, that some Euthanatos pawn of the Nephandi decided that the Technocracy was moving far too close to his Chantry, and wanted to remove the town in which his Chantry resided from the memory of the reality. That way, no one would be able to discover it and he could continue with his diabolical schemes undisturbed. Well, being a peon, he would contact his superiors and ask if they could do it, as he's just a peon. "Of course", they say, "we just love destroying things! You let us know when we've destroyed enough". So they set up the effect, and the townspeople would begin moving away for some unknown reason, the maps of the world would soon begin to re-write themselves, leaving out the town of, say, Dillon, Montana. Road-signs pointing to Dillon would start being hit by cars and not being repaired, etc. Now, what if something were to happen to this Nephandus pawn? Say, for example, that a member of his Chantry kills him? Well, his masters wouldn't stop at erasing the memory of the town. Hell no, they'd keep on going, destroying the Umbral representation, the townspeople who had moved would lose the rural kind of way of acting, etc. Eventually, the creation of Dillon, Montana would be eroded from the time-stream, and everyone who was ever born there would die or mysteriously 'disappear', any organization started there would fade from existance, until there would be nothing left of the town of Dillon, Montana.
Note that the reverse is also true, and that a concept can be 're-enforced', so that people would not forget about it. Say someone decided to decrease the amount of Entropy associated with Dillon, Montana. Public opinion would not degrade, the sense of community associated with towns would never be lost, the roads would not get as many potholes in the spring, etc. The town would just stop changing - no growth, no dimishment, just stasis. At higher levels, other aspects of the town would stop changing as well - the townspeople would just not get sick, or even age. Property would never need to be maintained, as they would not degrade, public opinion of the local government would never change, so the mayor at the time would never leave office, etc. At ludicrous levels of stasis, the town could freeze completely. Picture a really large Time 4 effect, freezing the town in time and space, but add on the fact that anyone thinking about the town of Dillon, Montana would not be able to think about anything else, as that would imply changing something that is associated with the frozen concept of Dillon, Montana.