"Spider" died. The death was so abrupt that none of the factions had time to react.
Previously, in order to thoroughly investigate the Cat-Tail Squad's disappearance, the Investigation Institute had not only dispatched Larkspur, an Inspector, to the scene, but had also sent two additional investigation teams.
These two new investigation teams had departed from the Magic Kingdom. With the mission urgent, they traveled day and night. Although the magical girls had done everything they could to reach Bai'an City as quickly as possible, none of them had expected Inspector Larkspur to move so swiftly.
She arrived in Bai'an City one day, located the enemy's lair the next morning, wiped out both its inhabitants and Nest that very night, and rescued the mission's targets—the Cat-Tail Squad.
The magical girls both admired and regretted it. They admired Larkspur's decisive, impressive actions; uncovering the truth and eliminating the enemy at top speed had always been the goal of the Investigation Institute's magical girls. But they also regretted that the matter had been resolved before they even arrived, meaning they had practically made the trip for nothing.
That disappointment, mixed with their hatred for the enemy, eventually turned into displaced anger.
The Investigation Institute magical girls who arrived later launched a carpet-bombing campaign of destruction against the remaining Black Ash Dawn forces in Bai'an City.
With Spider's death, Black Ash Dawn in Bai'an City became a scattered rabble with no leader. Having lost their sole leader and lacking enough strength to resist the magical girls, they naturally crumbled at the first blow and suffered total defeat.
At first, some evil believers capable of transforming still stubbornly resisted, attempting to use the Aberrant Beasts' power to escape alive. But under the magical girls' encirclement, they ultimately could not avoid death and were all executed.