The Deep void exists outside of, and separates, the Bubbleverses, and is a dimension of pure chaos and uncertainty. Due to its nature, not much is known about it. To this end, travel through this realm is near-impossible, as the Light Energy of any being or item is instantly dispersed upon contact.
Echoes are speculated to originate from The Deep Void. Their true forms parasitically leeching onto our Bubbleverse, casting shadows of themselves that mortals generally know as magic or Echoes.
The only confirmed instance of a successful Deep Void voyage is with the Gascoin Race, in which the invention of complete magic immunity, and the energy from destroying an entire Bubbleverse, were needed to complete the journey.