-----
The thousands of demons that Pandemonium had summoned to battle the Venerable of Flames didn't all die easily, upon the destruction of the inheritance trial building, the majority of them were sent flying away, most died, their souls, however, didn't.
Drake didn't bother teleporting them anywhere, but in that moment that the explosion happened, and space was distorted because the Venerable's divine realm bubble exploded, they all gathered together, hundreds of thousands of them, manifesting a demon gate by Pandemonium's orders.
He had tried to recycle the demon souls inside of the demon gate so he could gain more power but was distracted as Drake attacked him in the middle of all, unable to claim those souls, he abandoned them and no longer cared.
The demonic souls converged into a demon gate that, through the distortion of space, moved incredibly far away, collapsing near the ruins of an ancient civilization that lived here.