Dimensional Doors is a mod for Hexxit which allows you to create or enter things called pocket dimensions. These pocket dimensions are assessed with Dimensional Doors. These can either be player created areas, or spawned in by the game, depending on whether or not it was naturally generated.
Currently there are three different Dimensional Doors. These are the Dimensional Door, the Warp Door, and the Transdimensional Trapdoor. Each of these serve a different purpose. If you think of the pocket dimensions as levels, every Dimensional Door brings you down a level, and every Warp Door bring you up one level. So every time you go through a Dimensional Door without going back to the overworld, you need to go through a Warp Door to make up for it. However, the Transdimensional Trapdoor will bring you back to the overworld, no matter how far down you are from the surface. The catch with these are they are one-time use only, so don't use them unless you have to!
However, no matter what the risk may be, the reward of these pocket dimensions are worth it. If you create your own new pocket dimension, you get a 29x29x29 block area created for you, all within a 2x1x1 area. The pocket dimensions also seem to act exactly like the overworld, other than beds which will explode if you try sleeping in them and no mob spawning, which means you can grow trees, have farms, or anything else you can do in normal Minecraft. The only exception to this is if you replace enough Fabric of Reality blocks to lower the light level enough to spawn hostile mobs.
Rift Signatures, Rift Removers, and the Rift Blade
These are some more items integral to this mod. These allow you to either create, remove, or control the rifts which the core of this mod.
The Rift Signature can be used to create a manual link between two areas. This can create a link anywhere, from pocket dimensions to The Nether to The End. To create the rifts, just right click where you want the first rift to be, then right click again where you want the second rift to be.
The Stabilized Rift Signature differs in that it is not consumed after creating the second rift. Creating a third (and subsequent) rift requires that you have an Ender Pearl in your inventory. Although entering the third rift will take you to the first rift, it is a one-way trip, as re-entering the first rift will take you to the second rift, and not the third.
Next up is the Rift Remover, which will remove any rifts within a small area when activated. This is really only useful for if you want a pocket dimension permanently deleted, crafting the Rift Blade, or just want to clean up some rifts you may have left around.Finally, there is the Rift Blade. This blade can swap the orientation of a Dimensional Door or a Warp door, or create a temporary door through a rift. However, this blade can still be useful in a fight. While attacking with it, it will give you the abilities of an Enderman, causing you to do teleporting attacks with it.
Be wary of leaving an unopened rift lying around your home or anywhere on the Overworld/The End, as it attracts Endermen to it. Endermen have the ability to use these rifts to teleport and can also link these rifts to their destination. The trail between the rifts can destroy blocks in the vicinity, and the more rifts or trails there are, the more Endermen appear. Be sure to close all rifts, or set a door on them to prevent this damage.
Dimensional Dungeons are very dangerous to anyone who isn't experienced in the mod. Make sure to bring with you a Transdimensional Trapdoor, otherwise you could be stuck in one of them for a while. Dimensional Dungeons come in many different varieties. For example, some are laid with Piston Traps, while others can have surprise teleports to Limbo. However, even though the risk is high, the rewards are usually too great to pass up. You can get some of the best stuff from these, as long as you can avoid the traps laid for you. Just remember, the farther down you go, the harder it is to reach the surface. So far, it has not been noted that there is an end to how far you can go into these dungeons.
Sometimes mistakes happen. You're going through a Dimensional Dungeon and you fall into the void, or you're messing around with a friend on Multiplayer and he accidentally kills you. It's fine though, since Limbo exists. Limbo is the place which you go whenever you die within a dimensional pocket. Its a dark place filled with creatures called Monoliths and unraveled fabric. If you go into Limbo, you get to keep all your items that you had on you when you die. Also, while falling down into Limbo, if you look up you will see a open eye, and if you look down you will see a closed one. In order to get out of Limbo, you either need to die, which will make you lose all your items, make it to the bottom of Limbo and jump in the water, or find two columns of unraveled fabric, which mark a gateway to another dimension. If you get out of Limbo through the water however, you will get teleported to a random spot in the overworld, so make sure to bring a Rift Signature bound to your house and a Warp Door along for an easy way back. For more information, please check the wiki page for it here.
On certain occasions, a Rift Portal will show on the Overworld, but the player cannot pass through it to the next Dimension. They will instead walk right through it as if they were going the wrong way. This causes issues since it may be necessary for you to use for travel, blocks water from flowing in that block, or just looks out of place in a world. These Portals are placed two squares back on a block, rather than on the very first square, as seen by the image on the right.
When a Portal becomes troublesome, there is only one way to remove it. Using any item in your inventory, press Q and toss it through the face of the Portal, as the direction does count. This will trigger the Portal to teleport the item to the destination and create the closed Rift again. You can then use a Rift Remover to permanently close it or re-open it with a Dimensional Door or the Rift Blade.
Testing has shown that using a Stabilized Rift Signature and going through a completed linked rift is the cause of this. It will trigger one of the rifts to have the glitched door. There has been no note of an update fixing this as of yet.