Dream bubble

Dream Bubbles are celestial objects found in The Furthest Ring, glubbed into being by Horrorterrors. The Horrorterrors were convinced by Feferi to set up special bubbles for our protagonists to use. She was capable of negotiating with them due to her previous experiences with her Emissary Lusus, G'lbgolyb, having gotten her used to the nature of the Horrorterrors, as well as a possible method of directly contacting them (as Feferi's dream self was cut in half and her original body had a hole blown through the chest, she is probably rather glad that she set the system up).

The bubbles allow the players of Sburb/Sgrub who have lost a life to continue dreaming. The reality constructed in the bubbles is a combination of the memories of everyone inside the bubble accessible to any who has learned the bubble's nature. According to Aradia, it would be quite difficult to exit a bubble to get into a new one, however someone inside a bubble can travel to another one through common points in memory, taking their own memories with them to be integrated into the new bubble. These memories mix and combine, but in general no new memories are created.

Additionally, the bubbles store the consciousness of a player who has lost their dream selves and their original selves, making them double as a form of afterlife; the player is then capable of accessing the memory of anyone else who has gained access to the bubbles. Players who have ascended to the God Tiers wander through the dream bubbles when they are asleep, because their consciousness has already merged with that of their dream self. It is in this fashion that the bubbles can be used as meeting places between the dead and the living; even those from alternate universes and doomed timelines can be found in a bubble.

The bubbles can be physically entered as well, as Aradia was capable of pushing herself through a bubble's skin to re-observe the battle with Bec Noir, though she states that only those with mastery over time or space like she has are able to do this. Roxy has been shown to enter a bubble with ease, presumably meaning heroes of Void have some unspecified power relating to Space and/or Time. In it a whole planet was seen, populated with dead Trolls and visited by God Tier Rose and Dave. The planet itself has features of Earth, Alternia, Skaia, all 4 Planets of the Kids, and some of the Troll's Planets (LoQaM, LoPaH, LolCaT, LoTaF, LoCaS, corresponding to the Trolls that see Roxy).

Rose was able to accomplish a similar feat by piloting the severed moon of Derse into a bubble, although the program used to navigate was created by Dave, a hero of Time. However the trolls' ectobiology lab meteor has also passed through multiple dream bubbles possibility indicating they can be entered through brute force alone. This remains debatable however, as the meteor is propelled by the Maid of Time's powers and has the Sylph of Space on it.