Editing Demiplane (section)

===2nd Edition===
In the early days of 2nd edition, demiplanes still remained a DM tool; adventures like Isle of the Ape (WG6) continued in the same vein as the prior edition.

All that changed with Planescape.  In The Planewalker's Handbook, ''demiplane seed'' was available as an 8th-level spell to mages.  That book, and A Guide To The Ethereal Plane established that these "minor" demiplanes had to be created on the Ethereal Plane (probably because it was considered something of a proto-reality plane).  The process was pretty arduous, involving a pretty pricey gemstone and 100 days of spellcasting and other work, but otherwise, it did what it said on the box: you created your very own demiplane to fill with traps, treasure, whatever you felt you needed to keep up with.

There was also a 9th-level spell called ''demiplane decay'' that could destroy demiplanes under specific conditions, but it was pretty horrible overall; anyone who couldn't plane-hop out of the place was dissolved with the rest of the plane in the very end.

Special "major" demiplanes were beyond the scope of any mortal magic and were mainly the province of divine-level beings.