Astaroth, Phoenix, and Khalor were all smart enough to deduce that the invaders had something to keep bringing them back to life. It was easy to guess that such an item or structure existed.
But finding it, all the while fighting off thousands of players, was not a minor task. So they had bid their time.
They were certain Athena wouldn't have brought anything to their attention that wasn't at least that important. And now, with the whistling echoing in their ears, it would be easy to find.
All three of them dove out of the base over the southern wall in quick succession. Phoenix had been monitoring the fight from inside the tree's canopy, while Khalor was close to that wall doing his massacre run.
As for Astaroth, he was inside the tree and could rapidly orient himself in the right direction. All three could fly, so reaching their destination was easy for them.