Unnatural Weakness.

Legion-8 had ancestral trials to go through while he had nothing. If not for the mind network and the entertainment it brought, he would be tempted to break out of his egg early.

Legion-5 remained in his incubator for hundreds of years. It was almost a thousand years after his reincarnation that he finally got his freedom. He stopped growing for a while. His egg sensed that his potential had been saturated so it began to crack. He doesn't have neighbors in the womb to delay him so he hatched as soon as he was ready. 

"This can't be right. I am still weak." He said to himself when he sensed the change.

He can sense that his body is still weak. It is so weak that he can't move it much less use it to break out of his egg. But his egg doesn't care. Air entered through the cracks in the shell and reacted with the contents of his egg. The content began to turn bad and toxic. If he doesn't leave his egg soon then he will be poisoned to death.