I’ve been looking at the 8th-level spell Demiplane:
When the spell ends, the door disappears, and any creatures or objects inside the demiplane remain trapped there, as the door also disappears from the other side. Each time you cast this spell, you can create a new demiplane, or have the shadowy door connect to a demiplane you created with a previous casting of this spell.
This looks very useful as a portable shelter, or as a vault or prison for items or creatures the party needs to contain. I just have one question about the exact mechanics of the doorway.
If someone is inside the demiplane when the door closes, it explicitly says that they’re stuck there. (It doesn’t say that they can’t use teleport or plane shift, but that’s a separate question.) What it doesn’t say is whether I get stuck. Can you open the door back to your home plane if you’re inside?