"But before then, I need to know who 'she' is."
So Erden tapped into his connections with the goblins. Using that, he got a live feed from one of the goblin's visions. And Erden was a bit surprised at what he saw.
Right in front of a group of bowing goblins was a huge white stone. The white stone had ancient-looking colored drawings on it. In the middle of the stone was a large blue sphere, which Erden believed to his core. On the sides of his core's drawing was a row of green stickmen with different sizes, which were likely goblins and all other sub-races. Then the core is a drawing of a very big goblin. And below all that are a few drawings of goblins fighting kobolds and even giant wolves.
There was a lot of drawing on the rock, but it was clear that the dungeon core was the main focus of this whole thing. So it was clear who this 'blue mother' is.
Clearly it was him.