New World [1]
The original goal was to stop the spread of corruption into the Heavenly World.
Tiamat and the rest did their jobs perfectly. They eliminated the incoming threat with speed and precision so that the corruption didn't get further than they wanted it to.
But they couldn't stop it completely.
The corruption began spreading the instant the Foreign Races' vanguard entered the world. There was no way to stop that.
By the time the battle ended, an area the size roughly a hundred square feet in size was left rotted. In the pure white scenery of the principality, it stood out quite severely.
When Damien came back, it was the first thing he saw.
The people who'd come to deal with the crack had already retreated to recuperate.
Tiamat and the rest were the same. They were waiting for Damien to return while entertaining those who tried to make connections with them.