Demiplane question

[Crgaston]

The Demiplane spell states "Additionally, if you know the nature and contents of a demiplane created by a casting of this spell by another creature, you can have the shadowy door connect to its demiplane instead."

Is there any way to learn this information without the knowledge or consent of the creator of the original demiplane?

[Unoriginal]

The Demiplane spell states "Additionally, if you know the nature and contents of a demiplane created by a casting of this spell by another creature, you can have the shadowy door connect to its demiplane instead."

Is there any way to learn this information without the knowledge or consent of the creator of the original demiplane?

Sure, plenty. Research, divination, spying on the creator/stealing their notes, talking with other people who've been in that demiplane, etc

Maybe an Intelligence (Arcana) check could also reveal those infos, if someone can see the casting/the things the caster used for the casting of the spell, but that's DM-dependent.

[Crgaston]

Ok, cool, thanks! Is there a way to ward the demiplane against that sort of thing then?

[Asmotherion]

The Demiplane spell states "Additionally, if you know the nature and contents of a demiplane created by a casting of this spell by another creature, you can have the shadowy door connect to its demiplane instead."

Is there any way to learn this information without the knowledge or consent of the creator of the original demiplane?

The most direct way I can think of is a "Detect Thoughts" spell cast on the original caster., or someone who was with him when he last visited (example being his familiar).

Contact other Plane and Legend Lore, if used right may reveal a lot about both the user and the contenent of the plane. May be tricky to get everything right on one try though (especially dependent on the amount of contenent), but with enough time you'll either "guess" everything, or everything will be "revealed" to you.