A trap holding thousands of evicted demons, dropped into the Nothing to give them a way back to Sheol.
The second of the two items dropped into the portal by Justice Light's toppling trap. It held thousands of evicted demons along with the power to open a portal back to Sheol — if only they could find something to latch onto.
When it fell through the permanent doorway into The Nothing, the system announced that the Demon Trap had deactivated and all captured evicted demons were freed. Between the freed demons and the freed Bijou, four separate planes folded together, and the Nothing broke — after which it began draining into the Halls of the Ascendency, into Sheol, and into Scolopendra's Lair.
A trap device packed with thousands of evicted demons and the latent power to tear a portal back to Sheol.
Half of the two-part device that broke the Nothing, supplying the demons and the doorway back to Sheol.