For those who study Arcane magic nothing is impossible, and if there is any symbol of such might and power over nature it is the floating islands or planetoids. A relatively new invention, the floating planetoids offer wizards the ability to study and practice their art far away from prying eyes and errant distractions. Every island is different and unique to the wizard who created it.
The process of creating and shaping an floating planetoid is a long and expensive process, requiring a greater metamagic rod of shape earth, levitate and reverse gravity. The spell costs an additional 5,000 PP in resources (building materials, magic components, etc), on top of actually learning and developing the spell.
Wizard, Sorcerer, Alchemist, Witch level 9
Arcane casters can either develop the spell, requiring at least a year of study, or learn it from another Wizard who has the spell in his or her spellbook (costing however much the teacher wishes to offer and taking the better part of a month to learn the spell.)
Once the spell is learned it takes 5 days of uninterrupted casting to rend the land from the Earth, and the effect creates a floating landmass 1 sq. mile for every 10 levels the caster possesses. This can be performed multiple times, and the Earth shaped together by either the Shape Earth spell or earth elementals. It is up to the Wizard however, to determine how to keep himself hydrated and kept safe during the casting, as well as figuring out how to summon castles upon the planetoid, much less a dungeon and monsters or servants. Once created floating planetoids can be piloted by the caster, and they move at a speed of 50 miles per hour.
If all of these sounds a bit broken consider that there is only one NPC in all of GoHyaku that knows this spell. He is dead, and his Kobold apprentice has burned all of the spells in his spellbooks that the Kobold could not figure out on his own. This includes the book on creating floating planetoids. Also consider that there are only five planetoids in existence, and aside from the one the Kobold apprentice is inhabiting they are open for the taking, for anyone who can A, get to them and B, survive the labyrinthine traps and dungeons to get to the control room. Oh, did I mention that these dungeons were designed by a crazed wizard who somehow figured out how to create flying bits of rock? Use the Tomb of Horrors as a base and extrapolate from there. These islands should be a gift to players who work really hard and won’t simply crash the planet into a nearby town just because a bar wench didn’t give the Barbarian a “quickie”. I’m holding you responsible for any “accidents”, Mr. Dungeon Master.