The Iron Dimensional Door, when placed, creates a pocket dimension contained within zero space. Entering the door teleports the player to this strange world where the fabric of reality is laid bare, exposed and raw. More IDDs can be placed within the original pocket dimension, creating more, and this can be continued indefinitely. Each pocket created leads the player farther and farther from the light of the overworld.
The Wooden Warp Door creates a pocket dimension like the IDD, but this pocket dim is closer to the overworld rather than farther away. Eventually, placing enough WWDs will warp the player back to the overworld. Be warned, though, if you went to many dimensions down, you may arrive at a completely different location. Also, they do not create dimensions in the overworld.
The Trans-Dimensional Trapdoor acts as escape hatch, teleporting the player to whatever door first opened the pocket dim chain. Regardless of where the player places the hatch, it always sends the player to the opening of that group, unless they have ventured more that 6~8 iron doors down, away from the overworld. Then, the hatch has trouble finding the right way out.
Combining these various doors within the pockets allows an infinite variety of structures, built in between worlds, and linking them all together.
The use of doors, however, destabilizes and weakens space-time nearby. These unstable, pulsing tears in reality are called Rifts. Each rift leads to a specific pocket dimension, and are either created by breaking a Dimensional Door, or by finding them scattered across the surface of MC. When naturally generated, they often contain dungeons and other ruins. Placing a door over a Rift opens a passage leading to whatever exists on the other side of the Rift. To further manipulate these rifts, you also have the Rift Signature and the Rift Remover.
When the Rift Signature is used somewhere within a pocket dim. It remembers where, and upon use again in any other dim (including the overworld), it opens a rift to that location, linking those two dimensions. This process consumes the item, so it is single use only.
The Rift Remover, while expensive, is the only way to permanently eliminate Rifts. When activated near a rift, it closes that rift and propagates to other nearby rifts, closing all nearby Rifts that are currently interacting. It can be used several times before degrading completely.
Sometimes, you will find naturally created rifts that lead to pocket dimensions that contain ruins and dungeons. Within these ruins, chests will sometimes contain Fabric of Reality, and these can be used to craft Unstable Fabric. Unstable Fabric can be substituted for Ender Pearls in crafting the other items in this mod.