Okay, I was just reading the article in the Felarya Wiki on Lydus, or the "Astral Sea."
It's a very interesting read, offering insight into the cosmology of the multiverse Felarya resides in.
Then I was thinking, you know, this concept is very similar to the Blind Eternities in the Magic: the Gathering multiverse, representing the space between planes. People who travel Lydus are also referred to as "planewalkers..."
It wasn't long before I also realized how much the "outer-ones" resemble the Eldrazi in Magic (Eldrazi are the nigh-unkillable god-monsters that roam the Blind Eternities and devour entire planes from within. They were represented as creature cards in a recent set, and they're some of the largest and most destructive in the entire game. And it's still implied that they're only at a fraction of their full power in the set.)
Then there's the mention of the "Barrier of Reality," and how it separates Lydus from wherever the "outer-ones" dwell. In Magic, the Blind Eternities are much more dangerous than the wiki makes Lydus out to be, as only Magic's planeswalkers and other god-like beings can survive entering it directly.
Thus, I reached the conclusion: The Magic: the Gathering multiverse is on the other side of the "Barrier of Reality" in Lydus. The "outer-ones" are the Eldrazi.
What makes this so ironic is that, until they appeared as cards, they were all sealed away in the "Eye of Ugin" on the plane of Zendikar (a plane just as dangerous as Felarya, even without the Eldrazi devouring it from within.) The seal's just been broken, and after they devour Zendikar, they'll likely wander the rest of the Magic multiverse and recover their full power.