Arthur wasn't acting pessimistic. He wouldn't believe that such a grand prison would survive all this time thanks to the two forms of energies alone.
He believed there was still something hidden, some sort of trap. And that trap was designed to contain the originals, even if they came in such large numbers or held their full strength like now.
So he stayed behind while closely watching the attack of his originals. At the same time that gigantic ball of metal showed no signs of life at all, like the previous attack not only depleted the energies in this world, but also killed it.
"Rumble!"
Just before the one thousand originals would reach the ball, a sudden change occurred. The entire ball brimmed in flashes of strange white light that wasn't present before.
And with these flashes, the entire world rumbled like a thunderstorm was about to erupt here.
