Its cave-entrance is hidden by an illusion which only a wizard can penetrate. It leads to a staircase suspended in apparently infinite space glowing with shadowy light. At the bottom is the city of Mage's Rest, lit by glowing, bobbing orbs, full of ritual and mystery. Here, any wizard of any alignment can claim citizenship. Anyone casting a spell to harm another receives an immediate backlash in kind.
Many spells fail unless they're done for the greatest real good of the greatest number.
Conjuration-summonings done for a good purpose have the best possible result, while those for a bad purpose result in the summoned creature being uncontrolled. Divinations only work for groups of four or more folks seeking the greatest good for the greatest number of decent creatures. Necromancy only works for the common good. Animated dead turn on the caster, and death magic turns back on the caster. Wild mages lose two levels, and no surge is possible.