
Originally Posted by
Worldshaper
I'm not sure about the "rings in the sky" bit (although it adds another meaning to the Circle of Stars), but it does make sense that Sargeras might've broken part of the prison, perhaps destabilising the Worldsoul's containment in the process, and potentially causing its void-corrupted energies to start emerging again.
The Beledar, if it is indeed calcified Worldsoul-goo, sometimes goes dark since it happened, because it reflects the Worldsoul's current state. Sort of like a prism or something.
That's why the Beledar is depicted as a purple gem in Xal'atath's control (her Old God form) in that Azj-Kahet mural, because at the time the Worldsoul probably was corrupted and the Titans hadn't contained her in stasis yet.