Quickly checking myself, but you can create something of an ever expanding Demiplane with the spell Demiplane by casting it multiple times, right? So if the caster wanted, an even larger, vaster version of the Magnificent Mansion but permanent (and also you'd have to add the furnishings, servants, and functional internal structure (as desired)). Is that right, or am I misreading / making a bad interpretation of it?
Nothing about the spell lets you increase the size. You have two options when you cast it; create a new demiplane (of size 30ft x 30ft x 30ft) or connect to an existing demiplane. However, connecting to an existing demiplane doesn't modify it in any way other than adding a door.
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. 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.
I guess I misinterpreted it. The way I thought it worked was that you could create a Demiplane and then recast and have another 30' cube so adjacent to it that they would functionally become the same space. Kind of irritating.
Edit: To elaborate, I was trying to find an in universe RAW way to create something like 'The Folding Halls of Halas' from Critical Roles Campaign 2. Without resorting to DM Magic I mean.
You can link a Demiplane to another Demiplane by casting the spell within the first, but that doorway between the two will disappear when the spell ends, unless your DM lets you put some sort of seal on the portal between the two to make it permanent for as long as the seal is there. I don't think 5e technically has a spell or ritual that does that, but past editions of the game did, so it's not beyond reason. (And I believe this is exactly what Matt Mercer had in mind when he made the Folding Halls of Halas.)
Keep in mind, standard Demiplanes don't have an exit once the portal closes at the end of the hour, so if the portal you used to get in closes, you'll need to either Plane Shift or Banish yourself to get out, unless like the Folding Halls, or the permanent Magnificent Mansion in "The Joy of Extradimensional Space" in the Candlekeep Mysteries book, there's a password or other trigger to eject you back into the Material Plane.
Quickly checking myself, but you can create something of an ever expanding Demiplane with the spell Demiplane by casting it multiple times, right? So if the caster wanted, an even larger, vaster version of the Magnificent Mansion but permanent (and also you'd have to add the furnishings, servants, and functional internal structure (as desired)). Is that right, or am I misreading / making a bad interpretation of it?
Nothing about the spell lets you increase the size. You have two options when you cast it; create a new demiplane (of size 30ft x 30ft x 30ft) or connect to an existing demiplane. However, connecting to an existing demiplane doesn't modify it in any way other than adding a door.
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I guess I misinterpreted it. The way I thought it worked was that you could create a Demiplane and then recast and have another 30' cube so adjacent to it that they would functionally become the same space. Kind of irritating.
Edit: To elaborate, I was trying to find an in universe RAW way to create something like 'The Folding Halls of Halas' from Critical Roles Campaign 2. Without resorting to DM Magic I mean.
You can link a Demiplane to another Demiplane by casting the spell within the first, but that doorway between the two will disappear when the spell ends, unless your DM lets you put some sort of seal on the portal between the two to make it permanent for as long as the seal is there. I don't think 5e technically has a spell or ritual that does that, but past editions of the game did, so it's not beyond reason. (And I believe this is exactly what Matt Mercer had in mind when he made the Folding Halls of Halas.)
Keep in mind, standard Demiplanes don't have an exit once the portal closes at the end of the hour, so if the portal you used to get in closes, you'll need to either Plane Shift or Banish yourself to get out, unless like the Folding Halls, or the permanent Magnificent Mansion in "The Joy of Extradimensional Space" in the Candlekeep Mysteries book, there's a password or other trigger to eject you back into the Material Plane.