The Ends of All Things
Despite being populated by Primus, the Medium was not vacant before it was invaded by the storm of energy. The Astral Sea, across and between planes, was filled with eldritch beings, vast and awesome. Some call them Old Gods. Others simply call them hunger incarnate, simply waiting for a feast to arrive.
On occasion the hunger of one of these eldritch beings becomes so overwhelming, the vacuum in their stomachs so wide, that it collapses in on itself, creating another vortex. A black hole singularity that sucks in everything around it, and eventually dying away, unless continually sustained by infalling matter or energy adding to the collapsed mass. Near these singularities of destruction, the distinction between Astral Seas and the Ethereal divides between them, breaks down – the barrier between planes blurs and becomes hard to distinguish, and chaos and entropy grow exponentially.
These black holes, inescapable voids swallowing all are known collectively as Limbo. It is impossible to know where these Limbos lead – if anywhere – for nothing, no matter or information, can escape their event horizons. It is theorised that the energy they digest is funnelled back into the Motive, but these are nothing more than theories.
A vicious species of aberration, the Slaad’s natural ecosystem is in the accretion disk of a Limbo-black hole, hunting whatever is unfortunate enough to be dragged into it. Ironically, born out of immense hunger, the Slaad feast on everything that Primus has brought into the multiverse specifically for them to eat.
Nobody knows how they spread so ubiquitously across the Astral Sea, especially when their natural habitat appears to be around islands of all-consuming voids. However, they are seen nearly everywhere, suggesting some kind of planar transportation but nothing like the Slaad equivalent of The Conveyor is known to exist.