Kapitel 1285: More Than Surviving.

Apparently, every phoenix in the void universe is one of her soul fragments, not a few of them. So he wasn't unlucky when he met a soul fragment within an egg. Every phoenix egg has a soul fragment of hers within it. 

People think that Phoenixes are immortal because of their flames of rebirth but they are wrong about that. Phoenixes are immortal because of the great mother as their foundation. It is why no one has been able to copy their "divine ability."

The flames of rebirth is just a technique that uses spiritual energy to copy the properties of the grey water here. It destroys matter in the void universe and transforms it into energy capable of strengthening the soul. 

This energy is then transported to the great mother through the spiritual links between her and all her soul fragments. That is how the great mother has managed to acquire enough energy to become as powerful as demon gods.