Fluff question from Vigilus Ablaze (spoilers assumed)

[LordPathos]

Just wanted to know what the Voidclaw actually did besides essentially making a blackhole between Vigilus and its moon? I know it caused a lot of destruction and destabilized the planet a bit, but if his plan was to do something against the Nachmund Gauntlet, what did this blackhole do?

[LordPathos]

So I read a bit more of the book. Abby's main plan was to steal/destroy the blackstone spears that were creating the Nachmund Gauntlet. While not completely destroyed, the corridor is smaller now. Also, when the psychic connection was re-established with Vigilus, they got a message that the Planet Killer is coming to Vigilus' sister planet, Sangua Terra. I WONDER WHAT IT IS GOING TO DO!

While this is super neat an all, because if Sangua Terra is destroyed, I would assume that's enough to close the corridor then we would only have the one north of Macragge left. BUT WHAT DID THE VHULIAN ANOMALY DO?!
Was it only intended to be a weapon to cause more destruction so Imperium forces would have more to deal with while Abby went blackstone hunting?