The moment the Undead successfully occupied Luskan, the Space-Time Divine Artifact in the Alchemy Hall hurriedly devoured a large quantity of crystals to create an avatar for itself. However, the crystals it consumed did not come from the small box William had sent.
After obtaining that seemingly small yet actually enormous box, the Space-Time Divine Artifact used the crystals' energy to establish a small spatial transmission channel for itself. It used the location of the Time-Space Elementals in the Elemental Realm as a relay point, then connected directly to the God of Space-Time's Divine Kingdom.
Even if the God of Space-Time's Divine Kingdom had been sealed off, that did not mean William could not enter. Though the two had finally developed a few differences between them, they were still closer than even twins who shared the same heart.
That way, even if space on Toril was unstable, things could be temporarily stored in the Elemental Realm for a while.
The spatial channel was not large, but it was more than sufficient for delivering Energy Crystals to the Space-Time Divine Artifact. It was even enough for it to create a small avatar for itself.
The Divine Artifact then had Martha notify Hill, hoping he could send a Mage Tower Core capable of controlling an entire city, along with some matching constructs, to Luskan.
What that city needed was stability, something the Undead could not provide. The certainty of order had never had anything to do with them, even if they would obey it.
As for Laira, the Space-Time Divine Artifact thought she would be doing well if she could manage half as well as Lynn. Administrative ability had nothing to do with combat strength, yet on Toril... a ruler's capability was measured by combat strength.
More importantly... the Space-Time Divine Artifact