As I read it in the story bible, I though the formation of the shadow shard was a self-defense strategy because Rularuu was going to die if he didn't create a pocket dimension and fill it with shadows that he absorbed - like a vampire feeding on its own blood. Let's say you vision of the the dagger and well power is correct. If so, the wells represent bandwidths of power and there will always be a consistent amount of bandwidth in the multiverse. The dagger cuts off access to it and the more attached to it you are (more reliant on it as your source of power and how much bandwidth you draw) the more you suffer when the connection is severed (we are likely also buffered since we are on the slow path - we inherently have greater tolerance and less withdrawal from spike-and-dip power fluctuations due to discipline). Rularuu has to make his own dimension otherwise he will lose all the his connection, which persists through all dimensions. He has his section of bandwidth, and in a desperate "better to reign in hell than serve in heaven" maneuver allows his reality to be sacrificed to spare the connection.
The story bible (which may or may not have been canonical at the time of the shutdown - story lines after it was written could have superceded it in small parts, but I assume its reasonably close) states that the Shadow Shard was a magically created universe that was a shadow copy of Primal Earth's dimension, created by the Dagger of Jocas, and used as a decoy against Rularuu when he came to devour Primal Earth. It was intended to be devoured by Rularuu and collapse during the process, destroying him. Rularuu figured this out at the last instant and basically sacrificed a huge amount of his power to turn the shadow copy universe into a genuine dimension. That way it would not collapse and take Rularuu with it. But in the process he would be trapped within that dimension, with no obvious way to escape it, because he would have created a pocket dimension with no connections to our Primal Earth (does that sound familiar to anyone
).
However, although the process weakened Rularuu, by becoming the source of power of an entire cosmological dimension, in effect Rularuu has ascended to be a kind of Source. He's an Ascended being of sorts, but weaker in absolute power due to his unique dimensional circumstances. In particular, if the Shadow Shard is a dimension created by the Dagger of Jocas from a tiny sliver of all the beings on Primal Earth (or a subset of them) then it should have a tenuous connection to our Source. That, plus Rularuu's power which comes from a large number of consumed dimensions, makes him a kind of a unique composite being: indirectly a well-consumer like the Battalion, but also indirectly an ascended by virtue of being a form of well to the Shadow Shard.
I'd like to know of all possible dimensions how did portal corp get that one?
The story bible suggests that there are not an infinite number of dimensions, but just a huge number of them separated by some threshold of difference. Two dimensions that differ by only a tiny amount of changes tend to collapse into a single dimension representing both: to remain stable independent dimensions requires a significant difference in the timelines. Dimensional travel tends to land on closer, rather than farther dimensions, based on the degree of difference. For Primal Earth specifically, alone among most other dimensions, I think we can reach the Shadow Shard more easily than one might think because its a Shadow of Primal Earth specifically: its connection to Primal Earth via its creation through the Dagger of Jocas makes it "reachable" far more easily than it ought to be, and would be from any other dimension. In fact, by finding a way to the Shadow Shard, we had inadvertently presented a potential escape route for Rularuu that he himself could not have accessed without us. Oops.
Incidentally, I don't know who originally thought up that theory of cosmology for CoH, but hats off to them. Its basically the theory I reverse engineered as making the most sense given CoH's alternate dimension stories. It explains why so many of the dimensions we visit are either evil-goatee dimensions or world-gone-wrong dimensions. There simply aren't any dimensions where everything is the same except the Golden Gate Bridge is the Azure Gate Bridge, and dimensions where people are yellow, have five arms and speak by chirping are just too far away for Portal Corp to easily reach and travel to.
