Five Eighth Rank Invincibles were very patient.
Their target was not merely to kill the avatar of the Galaxy Master.
Instead, they aimed for the Galaxy Master to fall completely, so that not even the 'resurrection' of a Supreme Being could save him.
If it were only about killing an avatar, they could have made their move more than a decade ago when they sneaked outside the Milky Way Main Star.
Five Eighth Rank Invincibles, by sealing the space simultaneously, would ensure the Galaxy Master, even if capable of spatial transposition, would be trapped within the planet.
At that time, their joint attack on the Milky Way Main Star would overwhelm even a B-grade modified Planetary Defense System, which would last only a few breaths at most.
The Galaxy Master would have no escape, neither to heaven nor earth.