I have been wondering about this for a while now.
When I cast Demiplane and for example trick a bandit into entering the door, can I then cancel the spells effect and remove the door, trapping the bandit?
Or does it stay there until the hour is over?
Duration: 1 hour
The description isn't super clear on this aside from the time limit shown.
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.
Best Answer
No, you cannot end the effect of Demiplane early.
It is not a concentration spell, so you can't just stop concentrating to drop the effect. No part of its effect allows it to end prematurely at-will, either.
You'd need to either ensure the bandit is inside the demiplane when the spell expires. There are a lot of tools at your disposal to trick or ensnare the bandit to accomplish this task.